47results about "Network simulating resistances" patented technology

Described are controllable termination impedances that may be adjusted collectively by a combination of digital and analog signals. Each adjustable impedance, responsive to the digital signals, establishes a gross termination resistance for one of a plurality of communication channels by enabling one or more of a plurality of parallel-coupled impedance legs. Each leg includes at least one transistor for controlling the impedance of the leg over a continuous range. An analog compensation voltage is level shifted and the resulting level-shifted signal is applied to the control terminals of the transistors of the selected impedance legs. The compensation voltage, and consequently the level-shifted signal, varies with supply-voltage and temperature fluctuations in a manner that causes the collective impedance of the selected legs for each channel to remain stable despite the fluctuations. The combination of digital and analog impedance control provides for coarse impedance adjustments, such as to compensate for process variations, and additionally provides fine, adaptive adjustments to maintain the selected impedance despite changes in the supply voltage and temperature.

Apparatus and methods disclosed herein implement a MOS resistor using the current channel of a MOS transistor. The MOS resistance R(DS) is dependent upon MOS transistor geometry and nominal gate voltage. MOS resistor terminal-to-gate voltages are averaged and applied to the MOS transistor gate such as to maintain the MOS resistor terminal voltage to current ratio, resulting in a substantially constant R(DS). R(DS) is also compensated for temperature and process variations by adjusting gate voltages via negative feedback methods.

A low-noise reference voltages distribution circuit (10) is disclosed, comprising a multi-output voltage to current converter (V/I_Conv) adapted to receive an input reference voltage (V_R) for providing a plurality of output reference currents (I₁, . . . , I_N) to be converted into a plurality of local reference voltages (V₀₁, V_0N) at corresponding receiving circuits (LCR₁, LCR_N) adapted to be connected to said reference voltages distribution circuit (10). The multi-output voltage to current converter (V/I_Conv) comprises: -an input section (20) adapted to generate on the basis of said input reference voltage (V_R) a reference current (I₀), the input section (20) comprising a current mirror input transistor (M0E) having a voltage controlled input terminal (g_0E); -an output section (50) comprising a plurality of current mirror output transistors (M01, M0N) each adapted to provide a corresponding output reference current of said plurality of reference currents (I₁, . . . , I_N), each of said current mirror output transistors (M01, M0N) comprising a voltage controlled input terminal (g₀₁, . . . , g_0N), the output section (50) comprising a common input node (51) to which voltage controlled input terminals (g₀₁, g_0N) of said current mirror output transistors (M01, M0N) are connected. The voltage to current converter (V/I_Conv) comprises a low-pass filter (30) having an input node (31) connected to said voltage controlled input terminal (g_0E) of the current mirror input transistor (M0E) and an output node (33) connected to said common input node (51).

A tunable voltage-controlled pseudo-resistor structure, comprising: a symmetric PMOS transistor circuit and an auto-tuning circuit connected in series. Input of the auto-tuning circuit is connected to a central position V_f of the PMOS transistor circuit having its output V_g, with its purpose of keeping V_g−V_f at a constant value. The PMOS transistor circuit may produce body effect through various different bulk voltages. Through the auto-tuning circuit, V_g and V_f are kept constant to make current of transistor to produce compensation effect, such that regardless of V_a>V_b or V_a<V_b, a large resistance is maintained. Through utilizing the tunable voltage-controlled pseudo-resistor structure, constant resistance can be maintained under high input voltage, hereby reducing drifting of common-mode voltage, in achieving a superior resistance effect.

The invention belongs to the technical field of neural components, and particularly relates to a neuron circuit based on a memristor. The neuron circuit comprises an integral reset circuit, a resistance comparison circuit and a pulse output circuit, the integral reset circuit takes the current of an external circuit as the input, realizes the integration of the input current through the reset or setting operation of the memristor, and takes the monitoring voltage of the real-time resistance value of the memristor as the output. The resistance comparison circuit receives the real-time monitoring voltage, compares the real-time monitoring voltage with a voltage signal of a reference resistor, and outputs a resistance comparison result to the pulse output circuit; when the real-time monitoring voltage exceeds a threshold value, the pulse output circuit outputs a neural pulse signal to an external circuit and sends a feedback signal to the integral reset circuit, so that the memristor resistance of the integral reset circuit is reset. The method has the advantages of being low in area cost after integration, good in real-time performance and low in misoperation rate.

A pseudo resistor circuit and a charge amplifier include a first field effect transistor; a second field effect transistor having electrical characteristics matched with electrical characteristics of the first field effect transistor; and a voltage dividing circuit with terminal of a reference resistor electrically connected to a source terminal of the second field effect transistor. Further, a first operational amplifier with an output terminal is connected to a gate terminal of the first field effect transistor and a gate terminal of the second field effect transistor and in which midpoint voltage of the voltage dividing circuit is input into either an inverting or non-inverting input terminal and reference voltage is input into the other of the inverting and non-inverting input terminal. Furthermore, a second operational amplifier supplies voltage resulting from inversion and amplification of drain voltage of the first field effect transistor into the other terminal of the resistor.

The invention relates to a dual-current bias type CMOS (Complementary Metal Oxide Semiconductor) pseudo resistor, which comprises a first PMOS transistor, a second PMOS transistor, a first NMOS transistor, a second NMOS transistor and a buffer. The drain electrode of the first PMOS transistor is connected with the grid electrode of the first PMOS transistor. A substrate is connected with the source electrode of the first PMOS transistor, the grid electrode is connected with the grid electrode of the second PMOS transistor, and the source electrode is connected with the source electrode of thefirst NMOS transistor; the substrate of the second PMOS transistor is connected with the source electrode of the second PMOS transistor, the drain electrode of the second PMOS transistor is connectedwith the source electrode of the second NMOS transistor, and the source electrode serves as the first end of the CMOS pseudo resistor; the drain of the first NMOS transistor is connected with the grid of the first NMOS transistor, the substrate is connected with the source of the first NMOS transistor, and the grid is connected with the grid of the second NMOS transistor; the substrate of the second NMOS transistor is connected with the source of the second NMOS transistor, and the drain of the second NMOS transistor is used as the second end of the CMOS pseudo resistor; the non-inverting input end of the buffer is connected with the source electrode of the second PMOS tube, the inverting input end of the buffer is connected with the source electrode of the first PMOS tube, and the outputend of the buffer is connected with the source electrode of the first NMOS tube. The resistance value of the dual-current bias CMOS pseudo resistor is basically not affected by the process, temperature change and sub-threshold leakage current, and the robustness is good.

A MOS transistor including a first MOS transistor M1 to be used as a resistor; an input voltage source 1 connected to the source of the first MOS transistor for applying an input voltage Vin; and a gate voltage source 6 connected to the gate of the first MOS transistor for applying a gate voltage Vg. The gate voltage Vg and the input voltage Vin are set within a range where a gate-source voltage and source-drain voltage of the first MOS transistor cause the first MOS transistor to operate in a non-saturation region and also are set to avoid the first MOS transistor operating in an operation region with leakage current. Fluctuations of the resistance value resulting from a change in leakage current due to manufacturing variations are reduced and favorable temperature characteristics are obtained.

A diode connected P-type CMOS transistor is operated in the sub-threshold area and, with a bypass capacitor, operates as a low pass audio filter. The equivalent resistance of the CMOS transistor in the sub-threshold range is very high—in the gigaOhm range. With this size resistor, a capacitor in the 1-25 pF range may be used to provide filtering capabilities with break points in the 1-10 Hz frequency range. Such a filter provides an effective low pass filter that attenuates audio frequency signals. The 1-25 pF capacitors use little chip area making the arrangement practical for integrating on an IC with the audio signals. In one embodiment, a digital signal and the audio signals share one pin, where the audio signal appears only when the digital signal is high. In this case, the audio signal filtered out from the digital high signal. The filtered digital signal drives digital circuitry while the audio signal is directed to other audio circuitry.

A pseudo resistance circuit includes a first gate voltage adjustment circuit that adjusts respective currents of first and second current sources and also adjusts a gate voltage of a second field effect transistor to equalize or substantially equalize a drain voltage of the second field effect transistor and a voltage of a first end portion of a reference resistance element and controls a drain voltage of a first field effect transistor and the drain voltage of the second field effect transistor to maintain a constant or substantially constant relationship with each other; and a second gate voltage adjustment circuit that adjusts a gate voltage of the first field effect transistor to control the gate voltage of the second field effect transistor and the gate voltage of the first field effect transistor to maintain a constant or substantially constant relationship with each other.

This invention discloses an active load generation circuit and a filter. The active load generation circuit includes a transistor, a voltage control circuit, a voltage offset and tracking circuit, and a temperature sensing circuit. The transistor provides an impedance and includes a control terminal and an input terminal. The control terminal receives a control voltage, the input terminal receives an input signal, and the impedance is associated with the control voltage. The voltage control circuit generates an intermediate voltage according to a power supply voltage and a first reference voltage. The voltage offset and tracking circuit generates the control voltage according to the input signal and the intermediate voltage such that the control voltage varies with the input signal. The temperature sensing circuit senses an ambient temperature of the active load generation circuit and adjusts the first reference voltage according to the ambient temperature.

The present system provides a method for varying the value of passive components in electronic circuits. Passive components can range from basic resistors, capacitors, and inductors to complex, structures such as transmission lines and resonant cavities. Value selection and variation can either be dynamically performed during circuit operation or as a one-time part of the manufacturing process as determined by the requirements of the specific application. A digital-to-analog converter (DAC) circuit is used to input value selection data digitally, and control value selection with value resolution dependent on the resolution of the DAC. An alternate embodiment is provided for high frequency operation.

A resistance multiplier circuit coupled to a first node of a first circuit for providing a high-value resistance at the first node includes a first transistor, a second transistor being N times larger than the first transistor, and a resistor. In one embodiment, the first and second transistors are NPN bipolar transistors. The first transistor has its base and collector terminals coupled to the first node and an emitter terminal coupled to a second node. The second transistor has a base terminal coupled to the first node, a collector terminal coupled to a positive supply voltage, and an emitter terminal coupled to the second node. The resistor is coupled between the second node and a virtual ground node. When a voltage is applied to the first node, the resistance at the first node is (N+1) times the resistance of the resistor.

A MOSFET can operate as a resistor by operating in the linear or ohmic region of the drain V-I characteristics. This region can be obtained by floating the gate of the MOSFET, when the dc current and the voltage drop are given. Multiple resistors can be duplicated (or mirrored) by sharing the same source and floating gate. The floating gate voltage can be simulated using a closed loop equivalent circuit. Alternatively, the gate voltage can also be derived from the given drain-to-source voltage and the given current in a feedback loop. With this adaptive MOSFET resistor, the minimum supply voltage can be as low as the sum of the BJT threshold and the complementary BJT saturation voltage, e.g. V_CC≧V_BE+Vsat (e.g. 0.8+0.15<1.0V). The threshold voltage Vt should be less than V_BE.

Broadband analog radio-frequency devices can be used to create building blocks for scalable analog signal processors that operate over bandwidths of 50 MHz to 20 GHz or more. Example devices include integrators (transconductors), digitally controlled attenuators, buffers, and scalable summers implemented using deep sub-micron CMOS technology. Because the devices are implemented in CMOS, the ratio of trace/component size to signal wavelength is about the same as that of low-frequency devices implemented in printed circuit boards. Combining this scaling with high gain/high bandwidth enables implementation of feedback and programmability for broadband analog signal processing.

An electronic device including at least:

• • a reference resistor;
  • two first terminals between which the reference resistor is connected, and two second terminals between which a modified impedance value of the reference resistor is intended to be obtained;
  • a first circuit configured to apply between the two second terminals a voltage substantially equal to that between the two first terminals;
  • a second circuit configured to flow between the two second terminals a second current the value of which corresponds to a fraction of a first current for flowing in the reference resistor between the two first terminals.

A pseudo resistor with tunable resistance including a first transistor and a second transistor is provided. The first transistor has a first terminal, a second terminal and a control terminal. The first terminal of the first transistor serves as a first terminal of the pseudo resistor. The control terminal of the first transistor receives a control voltage. The first transistor is controlled by the control voltage, such that the first transistor operates in a weak inversion region. The second transistor has a first terminal, a second terminal and a control terminal. The first terminal of the second transistor is coupled to the second terminal of the first transistor. The second terminal of the second transistor and the control terminal of the second transistor are coupled to each other to serve as a second terminal of the pseudo resistor with tunable resistance. The second transistor operates in the weak inversion region.

Certain aspects of the present disclosure generally relate to generating a large electrical resistance. One example circuit generally includes a first transistor 210, 220 having a gate, a source connected with a first node 214 of the circuit, and a drain connected with a second node 216 of the circuit. The circuit may also include a voltage-limiting device 224, 226 connected between the gate and the source of the first transistor, wherein the device, if forward biased, is configured to limit a gate-to-source voltage of the first transistor such that the first transistor operates in a sub-threshold region. The circuit may further include a second transistor 212, 222 configured to bias the voltage-limiting device with a current, wherein a drain of the second transistor is connected with the gate of the first transistor, a gate of the second transistor is connected with the first node, and a source of the second transistor is connected with an electric potential.

The present invention provides a circuit arrangement to convert fixed, or grounded resistors, to floating resistors. In particular, the circuit arrangement provides for the coupling of active electrical resistance devices to provide a relatively high value electrical resistance between two non-grounded nodes of the circuit arrangement in the order of Giga-ohms. The invention further provides for the magnitude of the floating electrical resistance to be determined by the magnitude of electrical current supply thus providing a means to select the magnitude of the floating electrical resistance by selecting by selecting the magnitude of electrical current supply. The circuit arrangement requires relatively few active devices and consumes a relatively small amount of electrical power in operation. The floating resistor of the present invention may be used in applications where a relatively high value resistor consuming a relatively small area of silicon, exhibiting relatively good linearity and wide dynamic range are required. Applications for such a device include neural networks, image processing and vision systems.