Oscilloscope bias conditioning circuit based on impedance transformer

Abstract

The utility model discloses an oscilloscope bias conditioning circuit based on an impedance transformer, the signal input of the circuit firstly passes through a direct current bias circuit module, the direct current bias circuit module is used for controlling the direct current bias voltage of the input signal, and the direct current component and the alternating current component of the input signal are respectively conditioned; according to the utility model, in the full frequency band of DC-20GHz, the frequency response characteristic is superior to 1dB, and the direct-current bias voltage range can reach-1V to + 1V. In the full frequency band of DC-20GHz, the frequency response characteristic is superior to 1dB, and the direct-current bias voltage range can reach-1V to + 1V. Moreover, the broadband high-speed oscilloscope has relatively small insertion loss in the frequency band, can ensure the requirement of system output power, and can well meet the use of an actual system of the broadband high-speed oscilloscope. According to the utility model, the innovation capability and technical level in the electronic test and measurement field, data acquisition and processing, integrated circuits and the like in China are improved.

Description

Technical Field

[0001] The utility model relates to the field of broadband and high-speed conditioning circuits, in particular to an oscilloscope bias conditioning circuit based on an impedance converter. Background Art

[0002] In the oscilloscope test and measurement system, it is necessary to process AC-coupled and DC-coupled RF microwave signals, and the AC-coupled signal is often superimposed with a DC bias. The DC bias is also called analog bias. If designed properly, it can enable the oscilloscope to achieve optimal test performance.

[0003] The working principle of DC bias is to superimpose a DC voltage on the input signal. If the signal originally exceeds the analog-to-digital conversion (ADC) range of the oscilloscope, this bias can adjust the signal back to adapt to the input range of the ADC. Therefore, the utility model proposes an oscilloscope bias conditioning circuit based on an impedance converter, which is used to adjust the DC bias component of the input analog signal. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the utility model provides an oscilloscope bias conditioning circuit based on an impedance converter.

[0005] In this circuit, the signal input first passes through the DC bias circuit module, which is used to control the DC bias voltage of the input signal and condition the DC component and AC component of the input signal separately; then it passes through the balun single-ended to differential circuit module, enters the adjustable gain amplifier circuit module, and is output to the high-speed ADC chip module for signal acquisition. The adjustable gain amplifier can amplify small signals.

[0006] Furthermore, during conditioning, the DC bias voltage of the input signal is adjusted to be close to zero by adjusting the DC bias circuit module control voltage of the impedance converter;

[0007] When adjusting the bias voltage of the impedance converter, the source power supply pin is driven by the output voltage of a subtractor. The subtractor is implemented by an operational amplifier circuit. The positive input of the operational amplifier is a constant reference voltage, and the negative input is adjustable in size and ranges from 0V to +2V. The voltage range of the subtractor output is -1V to +1V, which is used to meet the source power supply voltage range requirements of the impedance converter.

[0008] Furthermore, the operational amplifier has a positive input of a constant reference voltage and a negative input of an adjustable voltage, both of which are provided by an impedance converter bias voltage control circuit consisting of a reference voltage source and an analog-to-digital converter DAC.

[0009] Furthermore, the DC bias voltage of the input signal is adjusted by a customized impedance converter, so as to process the AC analog signal with the superimposed DC bias component of the input broadband high-speed oscilloscope conditioning module.

[0010] Furthermore, the DC bias voltage of the input signal is adjusted by a customized impedance converter, which plays a role in balancing the processing of the AC analog signal with the superimposed DC bias component input to the broadband high-speed oscilloscope conditioning module.

[0011] Furthermore, the circuit uses AC coupling to remove the DC bias component.

[0012] Beneficial effects:

[0013] The utility model is an impedance converter-based oscilloscope bias conditioning circuit that uses AC coupling to remove the DC bias component, and then selects a more sensitive ADC range, making full use of the maximum resolution of the oscilloscope; at the same time, the DC bias component of the input signal can be accurately controlled, and the DC bias range of the oscilloscope can be flexibly and effectively designed. The utility model has a frequency response characteristic better than 1dB in the full frequency band of DC to 20GHz, and the DC bias voltage range can reach -1V to +1V. In addition, it has a small insertion loss in this frequency band, and can ensure the system output power requirements, which can well meet the use of broadband high-speed oscilloscopes in actual systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 A schematic diagram of an oscilloscope bias conditioning circuit based on an impedance converter provided in an embodiment of the utility model;

[0016] Figure 2 An impedance converter bias voltage driving circuit diagram of an oscilloscope bias conditioning circuit based on an impedance converter provided by an embodiment of the utility model;

[0017] Figure 3 An impedance converter bias voltage adjustment circuit diagram of an oscilloscope bias conditioning circuit based on an impedance converter is provided in an embodiment of the utility model. DETAILED DESCRIPTION

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other. The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0019] In order to meet the system usage and solve the above technical problems, the utility model designs an oscilloscope bias conditioning circuit based on impedance converter. Some oscilloscopes input analog signals without bias conditioning, and directly input them into ADC after amplification or attenuation conditioning. The bias range of the oscilloscope is determined by the input range of the amplifier / attenuator and ADC. This voltage range is generally very small. Alternatively, use AC coupling to eliminate DC bias; this method can only work when the DC component of the signal is very stable. If the DC power supply signal has ripples, the effect will not be very good.

[0020] In order to meet the system usage and solve the technical problems of the above two modes, the utility model designs an oscilloscope bias conditioning circuit based on impedance converter, the schematic diagram is as follows Figure 1 In the present invention, the DC bias component is removed by AC coupling, and then a more sensitive ADC range is selected, which fully utilizes the maximum resolution of the oscilloscope; at the same time, the DC bias component of the input signal can be accurately controlled, and the DC bias range of the oscilloscope can be flexibly and effectively designed.

[0021] Working principle of the circuit: In the oscilloscope bias conditioning circuit based on impedance converter of the utility model, a special impedance converter is designed, and the source voltage of the impedance converter is adjustable, thereby realizing the function of adjusting the DC bias component of the input analog signal.

[0022] The circuit includes: a DC bias circuit module, a balun single-ended to differential circuit module, an adjustable gain amplifier circuit module, and a high-speed ADC chip module;

[0023] The DC bias circuit module is used to control the DC bias voltage of the input signal and to separately condition the DC component and AC component of the input signal;

[0024] The balun single-ended to differential circuit module is used to convert a differential signal into a single-ended signal and also plays a role of common-mode suppression;

[0025] The adjustable gain amplifier circuit module is used to adjust the amplification factor according to the needs, and is composed of multiple cascaded amplifiers, and the gain of each amplifier is changed by adjusting the preset parameters;

[0026] High-speed ADC chips are used to perform high-frequency sampling of analog signals;

[0027] The signal input first passes through the DC bias circuit module, which mainly realizes the control of the DC bias voltage of the input signal and separately regulates the DC component and AC component of the input signal; then it passes through the balun single-ended to differential circuit module, enters the adjustable gain amplifier circuit module, and is output to the high-speed ADC chip module for signal acquisition. The adjustable gain amplifier can amplify small signals.

[0028] The DC bias voltage of the input signal is adjusted by a customized impedance converter, so that the DC bias and AC amplitude components of the wide range input signal of the input broadband high-speed oscilloscope conditioning module can be adjusted separately. The oscilloscope bias conditioning circuit based on the impedance converter is as follows: Figure 1 As shown. During adjustment, the DC bias voltage of the input signal is adjusted to be close to zero by adjusting the DC bias control voltage of the impedance converter. This ensures that when the input AC signal amplitude is very small, it needs to be amplified by a large multiple, so that the DC bias voltage is not large relative to the AC amplitude (AC gear), causing the waveform display to exceed the oscilloscope display waveform interface; or it is amplified by a small multiple, so that although the DC bias voltage is large relative to the AC amplitude (AC gear), the waveform display can still be within the oscilloscope display waveform interface, but the background noise of the oscilloscope will drown out the small AC amplitude.

[0029] When adjusting the bias voltage of the impedance converter, its source power supply pin is driven by the output voltage of a subtractor, which is implemented by an operational amplifier circuit. The positive input of the operational amplifier has a constant reference voltage (+1V), and the negative input is adjustable in size and has a range of 0V to +2V (a voltage twice the size of the positive reference voltage). In this way, the voltage range of the subtractor output is -1V to +1V, which meets the source power supply voltage range requirements of the impedance converter. The specific design of the subtractor and its peripheral circuits is as follows: Figure 2 shown.

[0030] The positive input reference voltage and the negative input adjustable voltage of the operational amplifier are provided by an impedance converter bias voltage control circuit composed of a reference voltage source and an analog-to-digital converter DAC. The specific design of the impedance converter bias voltage control circuit is as follows: Figure 3 shown.

[0031] By adjusting the DC bias voltage of the input signal through a customized impedance converter, a good balancing processing effect is played on the processing of the AC analog signal with the superimposed DC bias component of the input broadband high-speed oscilloscope conditioning module, which is more conducive to the subsequent amplification conditioning and acquisition circuits working in the amplitude and frequency range with the most full utilization of indicators.

[0032] The utility model of an oscilloscope bias conditioning circuit based on an impedance converter has been actually measured, and the frequency response characteristic is better than 1dB in the full frequency band of DC to 20GHz, and the DC bias voltage range can reach -1V to +1V. In addition, it has a small insertion loss in this frequency band, and can ensure the system output power requirements, which can well meet the use of broadband high-speed oscilloscope actual systems.

[0033] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various equivalent changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An oscilloscope bias conditioning circuit based on an impedance converter, characterized in that: The circuit includes: a DC bias circuit module, a balun single-ended to differential circuit module, an adjustable gain amplifier circuit module, and a high-speed ADC chip module; The DC bias circuit module is used to control the DC bias voltage of the input signal and to separately condition the DC component and AC component of the input signal; The balun single-ended to differential circuit module is used to convert a differential signal into a single-ended signal and also plays a role of common-mode suppression; The adjustable gain amplifier circuit module is used to adjust the amplification factor according to the needs, and is composed of multiple cascaded amplifiers, and the gain of each amplifier is changed by adjusting the preset parameters; High-speed ADC chips are used to perform high-frequency sampling of analog signals; In this circuit, the signal input first passes through the DC bias circuit module, then passes through the balun single-ended to differential circuit module, enters the adjustable gain amplifier circuit module, and then is output to the high-speed ADC chip module for signal acquisition. The adjustable gain amplifier can amplify small signals.

2. The oscilloscope bias conditioning circuit based on impedance converter according to claim 1, characterized in that: During conditioning, the DC bias voltage of the input signal is adjusted to be close to zero by adjusting the DC bias circuit module control voltage of the impedance converter; When adjusting the bias voltage of the impedance converter, the source power supply pin is driven by the output voltage of a subtractor. The subtractor is implemented by an operational amplifier circuit. The positive input of the operational amplifier is a constant reference voltage, and the negative input is adjustable in size and ranges from 0V to +2V. The voltage range of the subtractor output is -1V to +1V, which is used to meet the source power supply voltage range requirements of the impedance converter.

3. The oscilloscope bias conditioning circuit based on impedance converter according to claim 2, characterized in that: The positive input of the operational amplifier is a constant reference voltage, and the negative input is an adjustable voltage, both of which are provided by an impedance converter bias voltage control circuit composed of a reference voltage source and an analog-to-digital conversion DAC.

4. The oscilloscope bias conditioning circuit based on impedance converter according to claim 1, characterized in that: The DC bias voltage of the input signal is adjusted through a customized impedance transformer, which is used to process the AC analog signal with the superimposed DC bias component of the input broadband high-speed oscilloscope conditioning module.

5. The oscilloscope bias conditioning circuit based on impedance converter according to claim 1, characterized in that: The DC bias voltage of the input signal is adjusted by a customized impedance converter, which plays a role in balancing the processing of the AC analog signal with the superimposed DC bias component of the input broadband high-speed oscilloscope conditioning module.

6. The oscilloscope bias conditioning circuit based on impedance converter according to claim 1, characterized in that: This circuit uses AC coupling to remove the DC bias component.

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