Auto-calibrating transconductors for shunt voltage to digital power sequence conversion, error canceling references and current to power converters

Abstract

To provide a device for converting a detection voltage indicating a current conducted by a switching circuit into a series of electric pulses indicating power diffused by the switching circuit in response to the current.SOLUTION: A device includes a transconductor circuit including a first circuit for receiving a reference current and a first reference voltage and obtaining mutual conductance based on an automatically generated bias current, the reference current and the first reference voltage. A value of the mutual conductance is determined by the reference current and the first reference voltage. The transconductor circuit further includes a second circuit which is connected to the first circuit for receiving a detection voltage and generating a first current based on the detection voltage and the acquired mutual conductance.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This document relates generally, but not exclusively, to electronic circuits and, more particularly, to battery management systems. [Background technology]

[0002] Electric or hybrid-electric vehicles typically include one or more battery modules or other portable supplies configured to provide power to the vehicle's systems. In one example, an electric vehicle may include a set of one or more battery modules coupled in series to provide power at a specified voltage, such as a voltage in the range of 30 to 600 volts, to power or operate the vehicle's electric traction motor or other drivetrain system. The battery modules may be associated with a battery management system (BMS) configured to protect the battery modules from damage by controlling, such as by limiting or regulating, the power drawn from the modules during operation of the electric vehicle. In one example, the BMS may include control circuitry that limits the amount of current drawn from the battery modules by the electric vehicle's drivetrain system. The control circuitry may shut off the current drawn from the battery modules when the current or the power associated with the current exceeds the safe operating range of one or more components of the system. Summary of the Invention [Means for solving the problem]

[0003] One aspect of the present disclosure provides a device for converting a sensed voltage indicative of the current conducted by a switching circuit into a series of electrical pulses indicative of the power dissipated by the switching circuit in response to the current. A transconductor circuit comprising: a first circuit for receiving a reference current and a first reference voltage and obtaining a transconductance based on the automatically generated bias current and the reference current and the first reference voltage, wherein the value of the transconductance is determined by the reference current and the first reference voltage; a second circuit coupled to the first circuit for receiving the detected voltage and generating a first current based on the detected voltage and the obtained transconductance.

[0004] Another aspect of the present disclosure provides a system for converting a sensed voltage indicative of a current conducted by a switching circuit into a series of electrical pulses indicative of the power dissipated by the switching circuit in response to the current conducted by the switching circuit. a current-to-current converter circuit coupled to the transconductor circuit for receiving a first current indicative of the detected voltage, the current-to-current converter circuit comprising: a current squaring circuit for amplifying the first current by a calculation power of the first current; A current-to-current converter circuit is provided, the current-to-current converter circuit comprising a scaling circuit that scales the amplified first current based on a reference current to generate a second current.

[0005] Another aspect of the present disclosure provides a method for generating a signal indicative of power dissipated by a switching circuit, the method comprising: obtaining a sense voltage from the sense circuit indicative of a current conducted by the switching circuit; converting the sensed voltage into a first current by a transconductor circuit, the transconductor circuit having a selectable transconductance determined by a provided reference voltage and a provided reference current; converting the first current to a second current using a power law converter circuit based on the dynamic resistance of the switching circuit; integrating the second current onto a first capacitor; comparing the voltage on the first capacitor to a second reference voltage; generating an electrical pulse of the series of electrical pulses based on the comparing; and generating, by a compensation circuit, a second reference voltage based on the reference current and the timing signal, the reference having a value that automatically adjusts to compensate for variations in at least one of the capacitor value, the reference current, or the cycle time of the timing signal, thereby generating a series of one or more pulses indicative of the power dissipated by the switching circuit. [Brief explanation of the drawings]

[0006] [Figure 1] 1 illustrates an example of a battery management system. [Figure 2] 1 illustrates an example of a conversion circuit for converting current flowing through a switching circuit into a signal indicative of power dissipated as heat in a switching device. [Figure 3A] 1 illustrates an example of a circuit configured to derive a transconductance based on a provided reference current and a provided reference voltage. [Figure 3B] 1 illustrates an example of a circuit configured to convert a voltage to a current based on a provided transconductance. [Figure 4] 1 illustrates an example of a circuit configured to generate an output current proportional to a selectable exponent of an input current. [Figure 5] 1 illustrates an example of a circuit configured to generate an error-correction reference voltage.

[0007] In the drawings, which are not necessarily drawn to scale, like numerals may describe like components in different drawings. Like numerals with different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in this document. DETAILED DESCRIPTION OF THE INVENTION

[0008] Aspects of the present disclosure include techniques for controlling switching devices in a battery management system, such as a BMS used in an electric vehicle, to supply power from a battery module to a load (e.g., a vehicle motor) through the operation of one or more solid-state switching devices, such as one or more power gates. These techniques involve converting a sensed voltage, such as the voltage developed across a shunt resistor used in the BMS to sense current drawn from the battery module, into a series of electrical pulses; counting these pulses over time indicates the cumulative thermal energy or average thermal power dissipated in the BMS switching device during that time. The cumulative thermal energy in the switching device can indicate the current or instantaneous junction temperature of the switching device. The resulting series of electrical pulses can be combined with an appropriate algorithm and used to interrupt a current path in the BMS by controlling the switching device when the heat dissipated in the switching device exceeds the safe operating range of a protected battery module or supply. This can prevent or limit damage to the switching device due to cumulative heating caused by excessive operation or drawn current, and can protect the battery module or other system components, such as the electric motor, from operating under unsafe currents. These technologies enable BMS for high-voltage devices to be created using solid-state switches as the primary switching devices to control the power delivered to the load. The cost of these systems can be reduced by using solid-state devices rather than mechanical switches. Also, reliability and response time can be improved by controlling the operation of the switching devices based on the cumulative energy dissipated by the devices.

[0009] 1 illustrates an example of a battery management system 100. As shown in FIG. 1, the BMS 100 includes a battery module 105, a load 110, a switching circuit 115, a sensing device 120, and a monitoring circuit 125.

[0010] The battery module 105 may include a set of one or more electrochemical or solid-state battery cells configured to power the system. In one example, the battery module 105 includes a set of one or more battery modules arranged to provide power at a designated output voltage, such as 30 to 600 volts (V).

[0011] The load 110 includes an electrical or electromechanical circuit configured to be powered by power provided by the battery module 105. In one example, the load 110 is an electric motor, such as a DC motor used to provide mechanical power to the drivetrain of an electric vehicle.

[0012] The switching circuit 115 includes an electronic or electromechanical device configured to provide controlled or regulated power from a power source, such as the battery module 105, to drive or operate a load, such as the load 110. In one example, the switching circuit 115 includes one or more semiconductor devices, such as a field-effect transistor (FET), a power diode, or a power bipolar junction transistor, arranged to conduct current from the battery module 105 to the load 110. In another example, the switching circuit 115 includes at least one control signal, such as SWITCH_CTRL, that operates the switching circuit to control (e.g., limit or regulate) the current delivered from the power source through the switching circuit to the load. Such control may include limiting the amount of current or power drawn from the power source under a stated current or power. In one example, the switching circuit 115 includes a driver circuit (not shown) configured to receive the control signal and, in response to a value or other electrical characteristic of the control signal, drive one or more switching elements in the switching circuit 115, such as one or more semiconductor gates or transistors, to turn on or off to control the amount of current conducted through the switching circuit. In one example, switching circuit 115 includes one or more power FETs and one or more gate drivers arranged to controllably actuate the power FETs.

[0013] Sensing device 120 includes a device configured to detect the amount of power delivered by switching circuit 115. In one example, sensing device 120 includes a shunt resistor, or other circuit, coupled in series with switching circuit 115 and configured to generate a voltage indicative of the amount of current flowing through the sensing device or switching circuit.

[0014] The monitoring circuit 125 includes circuitry configured to monitor or control the operation of the BMS 100. In one example, the monitoring circuit 125 is configured with a hardware circuit or a software application to measure and store data indicative of electrical operating characteristics on one or more components of the BMS. In one example, the monitoring circuit 125 measures or calculates the voltage or charge remaining on the battery module 105, the current drawn by the load 110, or the temperature of the switching circuit 115. In one example, the monitoring circuit 125 is configured to control the operation of the switching circuit 115 based on a signal such as a sensed voltage generated by the sensing device 120. In one example, the monitoring circuit 125 is configured to turn off the switching circuit 115 based on an instantaneous or historical current conducted by the switching circuit 115. In another example, the monitoring circuit 125 is configured to turn off the switching circuit 115 based on instantaneous or historical heating in the switching circuit 115. The monitoring circuit 125 may include a conversion circuit 130, an accumulator circuit 135, and a logic circuit 140. In some examples, the monitoring circuit 125 includes a current reference 145 or a voltage reference 150. In other examples, the current reference 145 or the voltage reference 150 is obtained from an external circuit.

[0015] The conversion circuit 130 includes circuitry configured to convert a signal indicative of the current conducted by the switching circuit 115 into a signal indicative of, or proportional to, the amount of power consumed or dissipated by the switching circuit. In one example, the conversion circuit 130 converts an analog signal obtained from the sensing device 120, such as a voltage developed across a shunt resistor, into a digital signal, such as a series of electrical pulses, indicative of the average power or cumulative energy consumed or dissipated by the switching circuit 115. In one example, the frequency of the electrical pulses generated by the conversion circuit 130 is indicative of the consumed or dissipated power. In one example, the frequency of the electrical pulses generated by the conversion circuit 130 (e.g., the number of electrical pulses generated within an indicated span of time or period) increases in response to an increase in the amount of consumed or dissipated power. In another example, the frequency of the electrical pulses generated by the conversion circuit 130 decreases in response to a decrease in the amount of consumed or dissipated power.

[0016] Accumulator circuit 135 includes circuitry configured to accumulate, count, or store data indicative of the series of electrical pulses generated by conversion circuit 130. In one example, accumulator circuit 135 includes a counter, such as a binary counter circuit, configured to increment or decrement a stored counter value in response to each electrical pulse generated by conversion circuit 130. In one example, the counter is a Gray code counter configured to increment or decrement the counter value such that only one bit in the binary representation of the counter is changed with each increment or decrement.

[0017] Logic circuit 140 includes analog or digital logic circuitry configured to provide a control signal, SWITCH_CTRL, for controlling operation of switching circuit 115 based on the count of electrical pulses captured by accumulator circuit 135. In one example, logic circuit 140 checks for changes in these counts at indicated time intervals, such as every positive edge of a timing signal used to drive or activate the logic circuit. Logic circuit 140 includes memory or other hardware or software elements configured to implement an indicated technique or algorithm for selectively activating switching circuit 115 based on the count of electrical pulses captured by accumulator circuit 135. In one example, logic circuit 140 implements a technique for generating a control signal, such as SWITCH_CTRL, based on the count of electrical pulses generated by conversion circuit 130 within an indicated time span, such as an indicated number of cycles of timing signal CLK. Logic circuit 140 activates SWITCH_CTRL in response to determining that the number of electrical pulses generated by conversion circuit 130 within a specified number of cycles of timing signal CLK meets or exceeds a threshold number of electrical pulses, for example, as described in U.S. patent application Ser. No. 17 / 219,025, filed March 31, 2021, entitled "Fast Overcurrent Detection In Battery Management System," the contents of which are incorporated herein by reference. In one example, the threshold number of electrical pulses, or the indicated time span, is selected based on physical, electrical, or thermal characteristics of one or more components of BMS 100. Such characteristics may include results from simulations based on electro-thermal, electrical, and thermal models of the switching device with or without any heat sink, or datasheet parameters such as voltage or current tolerances, or characteristics of switching circuit 115. In various examples, logic circuit 140 enables configuring thresholds for multiple time spans to distinguish one or more conditions for controlling or interrupting power drawn by BMS 100.In one example, a first threshold may be used in a fast short circuit situation where a very fast response (e.g., real-time response or response within 1 microsecond) is desired to mitigate damage. In another example, a second threshold may be used in a slower overcurrent situation where damage to components may result if corrective action is not taken within an indicated time window, such as 1 microsecond to 100 milliseconds.

[0018] During operation, the BMS 100 is configured to provide current from the battery module 105 to the load 110, such as through control of the switching circuitry 115. Over time or under certain operating conditions, the switching circuitry 115 may degrade or become damaged, for example, due to cumulative heating that exceeds the circuit's junction temperature or other operating tolerances. Such heating and related damage may be caused by an increase or anomaly in the current drawn by the load 110, a malfunction in the battery module 105, a current spike, or other conditions that may cause the switching circuitry 115 to conduct more current or consume more power than specified by the circuit's indicated tolerances. A degraded or damaged switching circuitry may eventually fail, such as by remaining in an on or fully conductive state. Such a failure may result in damage to other components of the BMS 100 or failure of the entire system, such as during a short circuit or overcurrent event. In one example, a failure of the switching circuitry 115 may cause excessive current to be drawn from the battery module 105, causing damage to or destroying the module 105. The BMS 100 mitigates these problems by monitoring the current through the switching circuit 115 and turning off the circuit in response to detecting an event or condition that could damage the switching circuit. In one example, the BMS 100 monitors the current conducted by the switching circuit 115, such as the voltage developed across a shunt resistor (e.g., the sensing device 120), such as through operation of the monitoring circuit 125. The BMS 100 then determines whether to turn off the switching circuit based on the detected current, the physical characteristics (e.g., power or heat dissipation characteristics) of the switching circuit 115, and historical heating in the circuit. In some examples, these techniques can protect the switching circuit 115 from damage by turning off the switching circuit within a short time of the occurrence of an event that could damage the switching circuit. In one example, the logic circuit 140 can calculate an estimated junction temperature of the switching circuit 115 (e.g., the junction temperature of the switching device) using historical data generated by the sensing device 120, the conversion circuit 130, or the storage circuit 135.In one example, the turn-off action is triggered in response to the junction temperature, or estimated junction temperature, of the switching device approaching a threshold junction temperature, such as a maximum allowable junction temperature of the switching circuit.

[0019] 2 illustrates an example of a conversion circuit 200 for converting a current through a switching circuit, such as switching circuit 115, into a signal indicative of the power dissipated in the switching circuit. The conversion circuit 200 is an example of, or an element of, the conversion circuit 130. In one example, the conversion circuit 130 is an integrated circuit element of the analog front-end circuit of the BMS 100.

[0020] The conversion circuit 200 converts the reference voltage V REF , bias current I REF1 , and the sense voltage V s In one example, the reference voltage V is generated within the conversion circuit 200, such as by circuitry on the integrated circuit die on which the conversion circuit 200 is implemented. REF In another example, V ref is generated by a circuit external to the conversion circuit 200. The bias current I REF is generated within the conversion circuit 200 and has a nominal or indicated value and associated allowable variation in tolerance. s is a voltage signal obtained from a sensing device, such as a shunt resistor or sensing device 120, configured to generate a voltage response to the current I(t). s is the voltage developed across the shunt resistor or sensing device 120 in response to the current I(t).

[0021] In one example, the conversion circuit 130 converts the current I(t) to a frequency f proportional to the heating or power of a switching circuit (e.g., one or more switches or switching devices of the switching circuit 115) that conducts the current I(t). p The switching circuit generates an output signal, such as a pulse train or series of electrical pulses, having a frequency f pAn example of the proportional relationship between ρ and heating or power is shown in equations (1) and (2). The sum in equations (1) and (20) is calculated by dividing the elements E1 through E1 as shown in FIG. n on an element of the switching device or switching circuit 115 such as

[0022]

number

[0023] In equations (1) and (2), each exponential term

number

[0024] Equations (1) and (2) are derived based on the realization that current flowing through sensing device 120 may cause each element of switching circuit 115 to dissipate heat or consume power based on the resistance or impedance that each element exhibits or presents to the current. In one example, if element i has a constant resistance R ONI If we denote the current I s (t) and the power in the element P(t) iThere is a square relationship between the current I and the heating, as shown in equation (3). s (t) is the component of the current I(t) flowing through element i. In some examples, I(t) and I s (t) is the same current.

[0025]

number

[0026] In another example, element i is ondyn The current I flowing through the element is given by equation (4). s Dynamic resistance R is inversely proportional to (t) ondyn In this example, the power in element i is given by equation (5). An example of such a device is a device that generates a constant voltage drop, or a voltage drop that is substantially independent of the current flowing through the device, such as a diode. The power dissipated in such a device is proportional to the current flowing through the device because it is the product of the voltage drop across the device and the current flowing through the device. A dynamic resistance may be associated with such a device, such that the value of this dynamic resistance is represented by equation (4). In one example, in a diode or diode-based switching device, the voltage drop across the p-n junction of the diode remains substantially constant with large changes in current; therefore, the relationship between current and power in a diode is different from that in a power FET or resistor. While the power of a FET operating in the ON state may be expressed using the relationship shown in equation (3), the power in a diode may be expressed or approximated using the relationships shown in equations (4) and (5).

[0027]

number

[0028] In some embodiments, equation (5) may be expressed as the dynamic resistance R of element i of switching circuit 115. ondyn is the current I flowing through the element s (t) can be generalized using the recognition that the power dissipated in one of the components i of the switching circuit 115 can be better approximated as a non-integral exponential of (t). Thus, a generalized expression for the power dissipated in one of the components i of the switching circuit 115 can be written as shown in equation (6). In this equation, the dynamic resistance R ondyn The current I s The dependence on (t) is the current exponent n i Described in R oni is a constant.

[0029]

number

[0030] Total power P(t) of the switching circuit 115 total is the power contributed by each element P(t) as shown in equation (7). i is obtained by summing

[0031]

number

[0032] The sensing device 120 is connected to a shunt resistor R shunt In the example where s (t), and equation (7) can be written as shown in equation (8).

[0033]

number

[0034] constant C i is the scaling weight associated with element i of the switching circuit, and the voltage V s , and therefore the input current Is Each scaling weight C i may be converted to a positive integer using one or more normalization techniques, such as the interpreted multiplication of relation 8.2 by a shown or predetermined number or constant. Such techniques are useful for converting the fractional quantity C i Instead of the integer scaling constant G i can be used to relate the current to power relationship for each component of the switching circuit 115. The total normalized power in the switching circuit P N To obtain the corresponding equation (9) for (t), the associated equation can be transformed to a normalized integer scale.

[0035]

number

[0036] A proportionality constant K can then be incorporated into equation (9) to obtain a pulse train frequency proportional to the total normalized power of the switching circuit 115, as shown in equation (10).

[0037]

number

[0038] In one example, Equation 9 may be implemented as a sum of currents. Such current may be provided to a current-controlled oscillator to implement Equation 10. In one example, to implement Equation 9 as a sum of currents and Equation 10 as a current-controlled oscillator, conversion circuit 200 includes transconductor circuit 205, current converter circuit 215, and pulse quantization circuit 225. Conversion circuit 200 may further include gain circuits 210 and 220. The components of conversion circuit 200 may be configured to convert a frequency f p In one example, the gain circuits 210 and 220 are arranged to generate a series of electrical pulses having a scaling or normalized gain G iIn some embodiments, the gain G i is a programmable integral gain selected based on system or application requirements or specific device parameters.

[0039] The transconductor circuit 205 is a transconductor g m In one example, the transconductor circuit 205 includes a circuit configured to convert the received voltage into a current based on a sensed voltage V s , reference voltage V REF , and bias current I REF1 The transconductance gm is the input reference voltage V REF and the bias current I REF1 Then, as shown in equation (12), the transconductor circuit 205 determines the m Based on the current I 1i In one example, I1 is converted to G by the transconductor circuit 205 or the gain circuit 210. i and the scaled or weighted current I 1i-n and each scaled current I 1i is associated with element i of the switching circuit 115.

[0040]

number

[0041] The current converter circuit 215 converts an input current, such as I1, into a specified exponent n i The output current I has a magnitude proportional to out or I 2i In one example, the current converter circuit 215 has a transfer function given by equation (13) and, in combination with the gain circuit 220, provides an output current I 2i Generate.

[0042]

number

[0043] where the bias current to circuit 215, I REF2 is D×I REF1 and D is a usage-specific natural number user.

[0044] The pulse quantization circuit 225 converts the input current I 2、 or a circuit configured to generate a series of electrical pulses having a frequency proportional to the total power generated by the switching circuit 115. In one example, I2 is the current I shown in equation (14): 2i In one example, pulse quantization circuit 225 includes a proportional-to-current oscillator circuit that generates a signal having a frequency proportional to the input current. In another example, pulse quantization circuit 225 may generate a signal having a frequency proportional to the input current, as described herein. REF1 Internal voltage reference V that compensates for variations in REFQ In one example, the series of electrical pulses generated by the pulse quantization circuit 225 is provided to an accumulator circuit 135.

[0045] In one example, the oscillator circuit is coupled to the current-to-current converter circuit 215 and the compensation circuit. The oscillator circuit may include a capacitor that integrates the current I2 to generate a sense voltage. The oscillator circuit may couple the sense voltage to a reference voltage V REFQand generating an electrical pulse based on the comparison. In some embodiments, the oscillator circuit rapidly discharges the capacitor after generating each electrical pulse to reset the sense voltage to 0 volts. The oscillator circuit then resumes integrating the current I2 into the capacitor to generate the sense voltage. In one example, the oscillator circuit discharges the capacitor at a rate substantially higher than the frequency of the timing signal CLK (FIG. 1) so that the time spent discharging the capacitor is small or negligible compared to the period of the timing signal. In one example, the time spent discharging the capacitor is less than 1 percent of the period of the timing signal.

[0046] 3A and 3B collectively illustrate a transconductor circuit having a selectable or programmable transconductance. Such a transconductor circuit may be an example of transconductor circuit 205. The circuits illustrated in FIGS. 3A and 3B operate in a primary-secondary or server-client architecture. Primary circuit 300 includes a self-biasing circuit that generates a indicated transconductance gm based on a provided reference current and reference voltage. The value of the generated transconductance is determined by the ratio of the reference current to the reference voltage and is robust or tolerant to process, voltage, and temperature variations. Secondary circuit 360 generates a transconductance gm from primary circuit 300 based on a rotational voltage generated by primary circuit 300 generated in a process that generates a bias current. m The secondary circuit 360 is configured to replicate or capture V using the replicated transconductance. s The inverter is configured to generate a current proportional to a received input voltage, such as

[0047] 3A illustrates an example of a circuit 300 (e.g., a primary circuit) configured to obtain a transconductance based on a provided reference current and a provided reference voltage. The circuit 300 includes an input circuit 305 and a bias circuit 320. In one example, the input circuit 305 receives a differential voltage V REFM and VREFP In one example, the input transistors 310 and 315 are arranged to receive an input signal such as a voltage V REFM and V REFP is V REF =(V REFP -V REFM ) so that the input reference voltage V REF In another example, bias circuit 320 includes a cascode current mirror formed by transistors 335, 340, 350, and 355. Bias circuit 320 further includes a concatenated circuit, or stage, having transistors 325 and 330. In one particular example, transistors 310, 315, 325, and 330 are PFETs, and transistors 335, 340, 350, and 355 are NFETs.

[0048] In operation, bias circuit 320 determines the difference between the gate to source voltages of transistors 315 and 310, "V REF =V REFP -V REFM The differential current resulting from b =I REF1 Voltage V such that TUNE Transistors 310 and 315 are sized to operate in their linear region of operation, thereby generating V TUNE The drain to source voltage is defined as a differential current i b , which allows control of the value of V. Coupling transistors 325 and 330 have W / L ratios greater than the corresponding W / L ratios of transistors 310 and 315. The drains of transistors 310 and 315 are connected as source followers, so the source to drain voltages of transistors 310 and 315 are connected as source followers. TUNE are substantially identical (e.g., have values ​​that differ only by an indicated or acceptable margin of error) because the voltage drops on the source followers formed by transistors 325 and 330 in response to 2i b =I REF1A large V DS is required, the large V on transistors 310 and 315 is made weaker than transistors 325 and 330. DS reduces the sensitivity of circuit 300 to mismatches (e.g., due to process, temperature, or voltage variations) in the source followers formed by transistors 325 and 330. In one example, V REF =125mV and I REF1 = 1uA, V DS is approximately 1 V. Circuit 300 supplies a constant current I REF1 and a constant reference voltage (e.g., V REFP -V REFM ) The cascode current mirror formed by transistors 335, 340, 350, and 355, when together they form a current mirror amplifier with an output node at the drain of 335, receives I REF1 to a voltage at the drain of transistor 335. The connection between the drain of transistor 335 and the gates of transistors 325 and 330 converts the voltage V TUNE , which provides negative feedback that stabilizes circuit 300 by generating a current I that prevents excessive current I intentionally provided to the right-hand side of circuit 300. REF1 is the differential current 2i generated by transistors 310 and 315 b The large gain provided by the mirror current amplifier formed by transistors 335, 350, 340, and 355 causes the negative feedback to flow through the differential current 2i b Excess current I REF1 Compensate for the condition 2i b =g m· V REF =I REF1 is forced by negative feedback, so that the voltage V TUNE The modulation of the transconductance g m =I REF1 / V REF results.

[0049] Voltage V TUNE is the drain-to-source voltage V to the input transistors 310 and 315 through the cascode source follower transistors 325 and 330. DS Also, the change in transconductance, hence i b Since V can be caused by process, voltage, and temperature (PVT) variations, the operation of the bias circuit 320 uses negative feedback to regulate the voltage V TUNE By actively adjusting the transconductance g, the input transistors 310 and 315 can adjust the transconductance g based on the reference voltage and reference current provided over PVT variations. m In one example, the circuit 300 enables robust generation of I REF1 is always present and transistors 340 and 355 always conduct current due to the diode connections of transistors 340 and 355, so no start-up circuitry is required.

[0050] 3B illustrates an example of a circuit 360 (e.g., a secondary circuit) configured to convert a voltage to a current based on a provided transconductance. In the example, circuit 360 is substantially identical to circuit 300, with the exception that the gate of transistor 380 is not configured to receive any negative feedback, such as the negative feedback received at the gate of transistor 325. Circuit 360 converts a replicated voltage V from circuit 300. TUNE The circuit 360 operates as an open loop circuit having a transconductance defined by: Input circuit 365 and bias circuit 385. In one example, input circuit 365 couples the voltage V generated by sensing device 120 to the sIn another example, bias circuit 320 includes a pair of input transistors 370 and 375 arranged to receive an input signal such as . In another example, bias circuit 320 includes a cascode current mirror formed by transistors 387, 389, 390, and 395. Bias circuit 385 further includes a concatenated circuit, or stage, having transistors 380 and 384. In a particular example, transistors 370, 375, 380, and 384 are PFETs, while transistors 387, 389, 390, and 395 are NFETs.

[0051] In operation, circuit 365 applies V to the gates of transistors 380 and 384. TUNE This allows input transistors 370 and 375 to have the same V DS and thereby the current I B2 and causing transistors 370 and 375 to have the same transconductance (I REF1 / (V REFP -V REFM In the linear mode of operation, the current i generated by the bias circuit 385 b2 is the input voltage V s , and therefore the differential current generated by circuit 360 is proportional to the other input voltage V s (V INP -V INM ) in (I REF1 / (V REFP -V REFM The input circuit 365 has a transconductance of s In response to this, the current I 1i Output current I proportional to out Generates a current I out is expanded using a conventional current multiplier circuit to obtain the parameter G i This can be achieved.

[0052] Figure 4 shows the input current I INFIG. 4 illustrates an example of a circuit 400 configured to generate an output current proportional to a selectable exponent of . The output current I generated by the circuit 400 is an example of the converter circuit 215 or power law current converter circuit having the transfer function shown in equation (13). OUT is shown in equation (15).

[0053]

number

[0054] The term n is selectable through a resistor divider circuit 445 between values ​​of 1 and 2. Equation (15) can be derived from the bipolar junction transistor (BJT) current equation shown in equation (16), or equivalently, equation (16.1).

[0055]

number

[0056] In equation (16), I is the collector current, and I s is the reverse saturation current, and V be is the base to emitter voltage, and V t is the thermal voltage. In an example where all the BJTs in circuit 400 have the same size and a consistent layout, voltages V1, V2, and V3 can be obtained according to equations (16.2), (16.3), and (16.4). Equations (16.2), (16.3), and (16.4) are based on the approximation that these BJTs have a high emitter-to-base current ratio, and that most, or at least most, of the base current of each of transistors 410, 415, and 430 is compensated for by the circuit formed by transistors 405, 425, and 420.

[0057]

number

[0058] Equations (16.2) and (16.3) give the current I passing through these transistors. IN is a direct application of general equation (16.1) to transistors 440 and 435. Equation (16.4) shows that voltage V3 is obtained by subtracting the base-to-base voltage of transistor 430 from voltage V2. The base-to-emitter voltage of transistor 430 is given by the second term of equation (16.4) and by direct application of equation (16.1) to transistor 430. Current I REF2 is driven through transistor 430 by the current mirror formed by transistors 410 and 415. In this configuration, transistor 405 provides the base current for transistors 415 and 410. The current through transistor 405 is mirrored by transistors 425 and 420 to provide base current compensation for transistor 430. In an example where the input of voltage buffer 450 is connected or coupled to a voltage V3, such as node N3, then a current I generated in or conducted by transistor 455 OUT is given by applying equations (16) and (16.4) as follows:

[0059]

number

[0060] Similarly, when voltage buffer 450 has its input connected to a voltage V1, such as node N1, a current I generated in or conducted by transistor 455 OUT is given by application of equations (16) and (16.2) as follows:

[0061]

number

[0062] In some examples, the input of voltage buffer 450 is connected to a voltage V4 between voltages V1 and V3, such as at node N4, such as through resistive divider 445. In examples, resistive divider 450 has a large resistance value and therefore does not load nodes N1 and N3. The voltage V4 at the input of voltage buffer 450 can be expressed in terms of voltages V1 and V3 as follows:

[0063] V4=V1+n'(V3-V1), where 0 <n’<1(16.8)。

[0064] I OUT The value of can be obtained by substituting equation (16.8) for the value of voltage V4 and equations 16.2 and (16.4) for the values ​​of voltages V1 and V3, respectively, as shown in equation (16.9).

[0065]

number

[0066] Equation (16.9) can be further simplified to express the value of IOUT as shown in equation (16.10).

[0067]

number

[0068] Equation (16.10) is equivalent to equation (15) by the substitution n = 1 + n', where n' is a fraction less than identity and n has a value between 1 and 2.

[0069] In one example, circuit 400 includes FETs 420 and 425, BJTs 405, 410, 415, 430, 435, 440, and 455. Circuit 400 further includes a buffer circuit 450 and a turning resistor divider circuit 445.

[0070] In operation, transistors 435 and 440 are diode-connected, allowing the input current I IN Transistors 415 and 430 conduct the mirrored reference current I from transistor 410. REF2 Transistor 405 provides a base current to transistors 410 and 415. This base current is mirrored by transistors 420 and 425, allowing transistor 420 to provide a base current to transistor 430. Resistor divider 445 conducts an exponent n or n between 1 and 2, such that n=1 when voltage V4 at node N2 is equal to voltage V1, and n=2 when voltage V4 at node N1 is equal to voltage V3. i In some examples, two or more taps or electrical connections are connected to the resistor divider circuit 445 to obtain two or more output currents with different exponents of the input current in the range of 1 to 2.

[0071] Figure 5 shows the reference voltage V REFQ 5 illustrates an example of a circuit 500 (e.g., a reference circuit) configured to generate a reference voltage V REFQ is used by the pulse quantization circuit 225, such as an oscillator in the quantization circuit, to convert the current I2 into a series of pulses based on a comparison with a reference voltage. An embodiment of the circuit 500 is based on the following realization.

[0072] In a conventional oscillator, an input current, such as the current I2 provided by Equation (14), is stored on a capacitor until the voltage on the capacitor rises to a fixed or constant reference voltage. The voltage on the capacitor is compared to the reference voltage to generate a signal having a frequency proportional to the input current. As shown in Equation (14), the input current is proportional to the reference current I REF1 is proportional to the reference current I REF1 and therefore may have accuracy that is sensitive to or affected by variations in the reference current. This dependency is due to the fact that the reference voltage used by the oscillator is REF1 or the reference current I REF1The effects of the present invention can be eliminated or mitigated by relying on the

[0073] Also, the oscillator frequency may be inversely proportional to the capacitance value of the capacitor used to store or integrate the input current, and as a result, the oscillator frequency may vary with process variation in the capacitance value. This variation can be compensated for by ensuring that the oscillator reference voltage varies inversely with the capacitance value.

[0074] Additionally, variations in the timing signal used, for example, by accumulator circuit 135 or logic circuit 140 to count the number of pulses generated by conversion circuit 130 within a designated time span may cause variations or alter the number of pulses received within a designated time span. This may be true even if the current through sensing device 120 or switching circuit 115 is held constant. Such variations may be mitigated or compensated for by varying the oscillator reference voltage proportionally to the timing or clock signal frequency.

[0075] The above implementation is based on the reference voltage V according to equation (16). REFQ These can be combined and used to obtain

[0076]

number

[0077] In equation (17), N is a fixed number and t p is the number of timing signal cycles, and C is the capacitance value of the oscillator capacitor. In one example, N is the number of timing signal cycles shown, which may be selected based on the desired responsiveness or sensitivity of the reference voltage to variations in the timing signal frequency. REFQ The definition of I REF1The purpose of this is to reduce the influence of the dependency of the input current I2 on the variation of the capacitor value, the dependency of the oscillator frequency on the variation of the capacitor value, and the dependency of the pulse count on the variation of the timing signal frequency. p The reference current I flows through the capacitor C. REF is obtained by integrating

[0078] In one example, circuit 500 includes transistors 505, 510, 515, and 520. Circuit 500 further includes capacitor 525, capacitor 530, and resistor 535.

[0079] In operation, capacitor 525 conducts current I for N cycles of a timing signal, such as timing signal CLK shown in FIG. REF1 Capacitor 525 is charged by signal SAMP. Charging is stopped by deactivating signal CHARGE and activating signal CHARGE_B. Capacitor 525 is sampled by providing a short pulse on signal SAMP to transfer charge from capacitor 525 to capacitor 530. Capacitor C is then discharged by activating or driving signal RST. The process then repeats. After a short initial start-up time, the voltage on capacitor 530 has a value given by equation (17).

[0080] Various Examples

[0081] Example 1 is a device for converting a detection voltage indicative of a current conducted by a switching circuit into a series of electrical pulses indicative of the power dissipated by the switching circuit in response to the current, the device comprising a transconductor circuit including: a first circuit for receiving a reference current and a first reference voltage and obtaining a transconductance based on an automatically generated bias current and the reference current and the first reference voltage, wherein the value of the transconductance is determined by the reference current and the first reference voltage; and a second circuit coupled to the first circuit for receiving the detection voltage and generating a first current based on the detection voltage and the obtained transconductance.

[0082] In Example 2, the subject matter of Example 1 includes the first circuit including a first differential input circuit for receiving a first reference voltage and a bias circuit for receiving the reference current and generating the automatically generated bias current.

[0083] In Example 3, the subject matter of Example 2 includes, wherein the bias circuit is for automatically adjusting the automatically generated bias current in response to process, voltage, or temperature variations in the input circuit.

[0084] In Example 4, the subject matter of Examples 2-3 includes that the first differential input circuit comprises a differential field effect transistor (FET) circuit, and the bias circuit comprises a FET current mirror.

[0085] In Example 5, the subject matter of Examples 2-4 includes a coupling circuit for coupling the automatically-generated bias current to a second circuit, the second circuit being configured to generate the obtained transconductance using the coupled automatically-generated bias current.

[0086] In Example 6, the subject matter of Example 5 includes the second circuit including a second differential input circuit for receiving the detection voltage and a second bias circuit having a bias current determined by the coupled automatically generated bias current.

[0087] In Example 7, the subject matter of Example 6 includes the second differential input circuit comprising a differential field effect transistor (FET) circuit, and the second bias circuit comprising a FET current mirror.

[0088] In Example 8, the subject matter of Examples 1-7 includes a current-to-current converter circuit coupled to the transconductor circuit to receive the first current and generate a second current proportional to a configurable exponent of the first current.

[0089] In Example 9, the subject matter of Example 8 includes: an oscillator circuit coupled to the current-to-current converter circuit, the oscillator circuit comprising: a first capacitor that integrates a second current generated by the converter circuit to generate an integrated voltage, a comparison circuit that compares the integrated voltage with a second reference voltage, and an output circuit that provides the series of electrical pulses based on the comparison; and a reference circuit that generates the second reference voltage based on the reference current and a timing signal used to count electrical pulses in the series of electrical pulses, the reference circuit comprising: an integrator circuit having a second capacitor that integrates the reference current; and a control circuit that activates the integrator circuit to generate the second reference voltage based on the integration of the reference current for one or more cycles of the timing signal.

[0090] In Example 10, the subject matter of Examples 8-9 is such that the configurable exponent value of the first current indicates the dynamic resistance of the switching circuit.

[0091] Example 11 is a system for converting a detected voltage indicative of a current conducted by a switching circuit into a series of electrical pulses indicative of power dissipated by the switching circuit in response to the current conducted by the switching circuit, the system comprising: a current-to-current converter circuit coupled to a transconductor circuit to receive a first current indicative of the detected voltage, the current-to-current converter circuit comprising: a current squaring circuit for amplifying the first current by a calculation power of the first current; and a scaling circuit for scaling the amplified first current based on a reference current to generate a second current.

[0092] In Example 12, the subject matter of Example 11 includes, wherein the current-to-current converter circuit includes an adjustment circuit for selectively adjusting the computing power.

[0093] In Example 13, the subject matter of Example 12 includes, wherein the adjustment circuit is configured to selectively adjust the computing power to a value between 1 and 2.

[0094] In Example 14, the subject matter of Examples 12-13 includes, wherein the adjustment circuit includes a resistive divider for selectively adjusting the operating power to a value between 1 and 2.

[0095] In Example 15, the subject matter of Examples 12-14 includes the system further comprising a transconductor circuit including: a first circuit for receiving a reference current and a first reference voltage and obtaining a transconductance based on an automatically generated bias current and the reference current and the first reference voltage, wherein a value of the transconductance is determined by the reference current and the first reference voltage; and a second circuit coupled to the first circuit for receiving a detection voltage and generating a first current based on the detection voltage and the obtained transconductance.

[0096] In Example 16, the subject matter of Example 15 includes: an oscillator circuit coupled to the current-to-current converter circuit, the oscillator circuit including a first capacitor for integrating a second current generated by the converter circuit to generate an integrated voltage, a comparison circuit for comparing the integrated voltage with a second reference voltage, and an output circuit for providing a train of electrical pulses based on the comparison; and a reference circuit for generating the second reference voltage based on a reference current and a timing signal used to count electrical pulses in the train of electrical pulses, the reference circuit including an integrator circuit having a second capacitor for integrating the reference current and a control circuit for operating the integrator circuit to generate the second reference voltage based on an integration of the reference current for one or more cycles of the timing signal.

[0097] Example 17 is a method for generating a signal indicative of power dissipated by a switching circuit, the method including: obtaining a sense voltage indicative of current conducted by the switching circuit from the sense circuit; converting the sense voltage to a first current by a transconductor circuit, the transconductor circuit having a selectable transconductance determined by a provided reference voltage and a provided reference current; converting the first current to a second current using a power law converter circuit based on a dynamic resistance of the switching circuit; integrating the second current onto a first capacitor; comparing the voltage on the first capacitor to a second reference voltage; generating a series of one or more electrical pulses based on the comparison; and generating a second reference voltage by a compensation circuit based on the reference current and a timing signal, the reference having a value that automatically adjusts to compensate for variations in at least one of the capacitor value, the reference current, or a cycle time of the timing signal, thereby generating a series of one or more pulses indicative of power dissipated by the switching circuit.

[0098] In Example 18, the subject matter of Example 17 includes, wherein the sensing circuit comprises a shunt resistor coupled in series with the electrical circuit.

[0099] In Example 19, the subject matter of Examples 17-18 includes generating the second reference voltage includes integrating a reference current into a second capacitor for one or more cycles of a timing signal, a cycle of the timing signal indicating a unit of time for determining power dissipated by the switching circuit based on the one or more pulses.

[0100] In Example 20, the subject matter of Examples 17-19 includes the power law converter circuit converting the first current to the second current based on the dynamic resistance of the switching circuit by amplifying the first current to generate an intermediate current having an amplitude that is a selectable function of the amplitude of the first current, and scaling the intermediate current proportionally to a reference current to obtain the second current.

[0101] Example 21 is at least one machine-readable medium comprising instructions that, when executed by a processing circuit, cause the processing circuit to perform operations to implement any of Examples 1-20.

[0102] Example 22 is an apparatus equipped with means for carrying out any one of Examples 1 to 20.

[0103] The twenty-third embodiment is a system for carrying out any one of the first to twentieth embodiments.

[0104] Example 24 is a method for carrying out any of Examples 1-20.

[0105] The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the subject matter of the present invention may be practiced. These embodiments are also commonly referred to as "examples." Such examples may include components in addition to those shown or described. However, the inventors also contemplate examples in which only the components shown or described are provided. Furthermore, the inventors also contemplate examples using any combination or permutation of those components (or one or more aspects thereof) as shown or described with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein. In the event of a conflicting usage between this document and a document so incorporated by reference, the usage in this document shall control.

[0106] In this document, the term "a" is used, as is common in patent documents, to include one or more, regardless of any other instance or usage of "at least one" or "one or more." In this document, the term "or" is used to refer to non-exclusive, or "A or B" to include "A but not B," "B but not A," and "A and B," unless otherwise indicated. In this document, the terms "comprise" and "in which" are used as the plain English equivalents of the terms "comprise" and "wherein," respectively. Also, in the following claims, the terms "comprise" and "comprising" are open-ended, i.e., systems, devices, articles, compositions, formulations, or processes that include elements in addition to the elements listed after such terms in the claim are still considered to be within the scope of that claim. Furthermore, in the following claims, the terms "first," "second," "third," etc. are used merely as labels and are not intended to impose numerical requirements on their objects.

[0107] As used herein, the term "connected" means a direct electrical connection between the things connected, without any intermediary devices. The term "coupled" includes either a direct electrical coupling between the things coupled, or an indirect coupling through one or more passive or active intermediary devices. The term "circuit" corresponds to one or more passive and / or active components arranged to cooperate with each other to provide a desired function. The term "signal" means at least one current signal, voltage signal, or data signal, such as an analog signal, a digital signal, or a mixed analog and digital signal.

[0108] The example methods described herein may be implemented, at least in part, by a machine or computer. Some examples may include a computer-readable or machine-readable medium encoded with instructions operable to configure an electronic device to perform the methods described in the examples above. Implementations of such methods may include code, such as microcode, assembly language code, higher-level language code, etc. Such code may include computer-readable instructions for performing various methods. The code may form part of a computer program product. Further, in examples, the code may be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media may include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memory (RAM), read-only memory (ROM), etc.

[0109] The above description is intended to be illustrative, not limiting. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used, for example, as may be apparent to one of ordinary skill in the art upon reviewing the above description. The Abstract is provided in accordance with 37 C.F.R. §1.72(b) to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together in a manner that streamlines the disclosure. This should not be construed as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may reside in less than all features of a particular disclosed embodiment. Accordingly, the following claims are incorporated herein as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the inventive subject matter should be determined with reference to the appended claims, along with the full range of equivalents to which such claims are entitled.

Claims

1. 1. A device for converting a sensed voltage indicative of a current conducted by a switching circuit into a series of electrical pulses indicative of power dissipated by said switching circuit in response to said current, said device comprising: A transconductor circuit comprising: a first circuit for receiving a reference current and a first reference voltage and deriving a transconductance based on an automatically generated bias current and the reference current and the first reference voltage, wherein the value of the transconductance is determined by the reference current and the first reference voltage; a second circuit coupled to the first circuit for receiving the detected voltage and generating a first current based on the detected voltage and the obtained transconductance; a pulse quantization circuit coupled to an output of the transconductor circuit and configured to generate the series of electrical pulses indicative of power dissipated by the switching circuit in response to the current conducted by the switching circuit; A device comprising:

2. The first circuit comprises: a first differential input circuit for receiving the first reference voltage; a bias circuit for receiving the reference current and for generating the automatically generated bias current.

3. 3. The device of claim 2, wherein the bias circuit is for automatically adjusting the automatically generated bias current in response to process, voltage, or temperature variations in the first differential input circuit.

4. the first differential input circuit comprises a differential field effect transistor (FET) circuit; The device of claim 2 , wherein the bias circuit comprises a FET current mirror.

5. 3. The device of claim 2, further comprising a coupling circuit for coupling the automatically generated bias current to the second circuit, the second circuit configured to generate the obtained transconductance using the coupled automatically generated bias current.

6. the second circuit includes a second differential input circuit for receiving the detection voltage; a second bias circuit having a bias current determined by the coupled automatically generated bias current.

7. the second differential input circuit comprises a differential field effect transistor (FET) circuit; The device of claim 6 , wherein the second bias circuit comprises a FET current mirror.

8. 10. The device of claim 1, further comprising: a current-to-current converter circuit coupled to the transconductor circuit to receive the first current and to generate a second current proportional to a configurable index of the first current.

9. an oscillator circuit coupled to the current-to-current converter circuit, the oscillator circuit comprising: a first capacitor that integrates the second current produced by the current-to-current converter circuit to produce an integrated voltage; a comparison circuit for comparing the integrated voltage with a second reference voltage; an oscillator circuit comprising an output circuit for providing the series of electrical pulses based on the comparison; a reference circuit for generating the second reference voltage based on the reference current and a timing signal used to count electrical pulses in the series of electrical pulses, the reference circuit comprising: an integrator circuit having a second capacitor for integrating the reference current; and 9. The device of claim 8, further comprising: a reference circuit comprising control circuitry for operating the integrator circuit to generate the second reference voltage based on an integral of the reference current for one or more cycles of the timing signal.

10. The device of claim 8 , wherein the value of the configurable exponent of the first current is indicative of a dynamic resistance of the switching circuit.

11. 1. A system for converting a sensed voltage indicative of a current conducted by a switching circuit into a series of electrical pulses indicative of power dissipated by the switching circuit in response to said current conducted by the switching circuit, the system comprising: a current-to-current converter circuit coupled to the transconductor circuit for receiving a first current indicative of the detected voltage, the current-to-current converter circuit comprising: a current squaring circuit for amplifying the first current by a calculation power of the first current; and a current-to-current converter circuit including a scaling circuit that scales the amplified first current based on a reference current to generate a second current; a pulse quantization circuit coupled to an output of the transconductor circuit and configured to generate the series of electrical pulses indicative of power dissipated by the switching circuit in response to the current conducted by the switching circuit; A system comprising:

12. 12. The system of claim 11, wherein the current-to-current converter circuitry includes an adjustment circuitry for selectively adjusting the computing power.

13. The system of claim 12 , wherein the adjustment circuitry is configured to selectively adjust the computing power to a value between 1 and 2.

14. 13. The system of claim 12, wherein the adjustment circuitry includes a resistive divider for selectively adjusting the computing power to a value between 1 and 2.

15. The system comprises: A transconductor circuit comprising: a first circuit for receiving the reference current and a first reference voltage and obtaining a transconductance based on an automatically generated bias current and the reference current and the first reference voltage, wherein a value of the transconductance is determined by the reference current and the first reference voltage; and 13. The system of claim 12, further comprising: a transconductor circuit comprising: a second circuit coupled to the first circuit for receiving the detected voltage and generating the first current based on the detected voltage and the obtained transconductance.

16. an oscillator circuit coupled to the current-to-current converter circuit, the oscillator circuit comprising: a first capacitor for integrating the second current produced by the current-to-current converter circuit to produce an integrated voltage; a comparison circuit for comparing the integrated voltage with a second reference voltage; an oscillator circuit comprising an output circuit for providing the series of electrical pulses based on the comparison; a reference circuit for generating the second reference voltage based on the reference current and a timing signal used to count electrical pulses in the series of electrical pulses, the reference circuit comprising: an integrator circuit having a second capacitor for integrating the reference current; and 16. The system of claim 15, further comprising: a reference circuit comprising control circuitry for operating the integrator circuit to generate the second reference voltage based on an integral of the reference current for one or more cycles of the timing signal.

17. 1. A method for generating a signal indicative of power dissipated by a switching circuit, the method comprising: obtaining a sense voltage from a sense circuit indicative of a current conducted by the switching circuit; converting the sensed voltage into a first current by a transconductor circuit, the transconductor circuit having a selectable transconductance determined by a provided reference voltage and a provided reference current; converting the first current to a second current using a circuit configured to implement a power law current converter based on a dynamic resistance of the switching circuit; integrating the second current onto a first capacitor; comparing the voltage on the first capacitor to a second reference voltage; generating an electrical pulse of the series of electrical pulses based on the comparison; and generating, by a compensation circuit, the second reference voltage based on the reference current and a timing signal, the second reference voltage having a value that automatically adjusts to compensate for variations in at least one of a capacitor value, a reference current, or a cycle time of the timing signal, thereby generating a series of one or more pulses indicative of power dissipated by a switching circuit.

18. 20. The method of claim 17, wherein the sensing circuit comprises a shunt resistor coupled in series with an electrical circuit.

19. Generating the second reference voltage includes:

18. The method of claim 17, comprising integrating the reference current into a second capacitor for one or more cycles of the timing signal, a cycle of the timing signal representing a unit of time for determining power dissipated by a switching circuit based on the one or more pulses.

20. The circuit configured to implement the power law current converter comprises: amplifying the first current to generate an intermediate current having an amplitude that is a selectable fraction of the amplitude of the first current; and 18. The method of claim 17, further comprising converting the first current to a second current based on a dynamic resistance of the switching circuit by scaling an intermediate current proportional to the reference current to obtain the second current.

Images