CMOS variable gain amplifier circuit with high dynamic range

Abstract

The invention relates to the technical field of integrated circuit design, in particular to a CMOS variable gain amplifier circuit with a high dynamic range, which comprises an amplifier U, wherein a resistor Rin1 is connected in series between Vin+ and the positive input end of the amplifier U, a resistor Rin2 is connected in series between the Vin- and the positive input end of the amplifier U, a resistor Ri1 is connected in series between the Vout+ and the positive output end of the amplifier U, a resistor Ri2 is connected in series between the Vout- and the negative output end of the amplifier U, a resistor Rf1 is connected in series between the V'in+ and the V'out-, a resistor Rf2 is connected in series between the V'in+ and the Vout+, a resistor Rf3 is connected in series between the V'in-and the V'out+, and a resistor Rf4 is connected in series between the V'in-and the Vout-. The driving capability and the operation stability of the gain amplifier circuit are ensured.

Description

technical field [0001] The invention relates to the technical field of integrated circuit design, in particular to a high dynamic range CMOS variable gain amplifier circuit. Background technique [0002] Analog circuits generally need to amplify or attenuate the signal so that the amplitude of the output signal remains at a reasonable level, and the circuit module used to realize this function is called a variable gain amplifier (VGA). The indicators to measure VGA generally include: gain control accuracy, controllable gain range, linearity, power consumption, noise and bandwidth. [0003] The signal to control the gain can be divided into analog signal or digital signal. Among them, the VGA controlled by analog signal is a traditional circuit structure with a very limited range of adjustable gain, which is basically consistent with the variable range of the control signal; in addition, changes in temperature and process parameters , it is easy to cause changes in the gain ...

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Problems solved by technology

[0003] The signal to control the gain can be divided into analog signal or digital signal. Among them, the VGA controlled by analog signal is a traditional circuit structure with a very limited range of adjustable gain, which is basically consistent with the variable range of the control signal; in addition, changes in temperature and process parameters , it is easy to cause changes in the gain curve, especially at low gains, random changes caused by various factors can easily overwhelm the gain changes caused by the control signal

[0004] The VGA controlled by digital signal has the feature of programmable, but it is difficult to guarantee the linearity in a large gain range when changing the DC operating point of the circuit at the same time of operation. In addition, the performance of this open-loop circuit is easily affected by temperature and process. influences

[0005] like figure 1 Shown is the schematic diagram of the existing analog open-loop variable gain amplifier circuit, the dynamic range and linearity are greatly limited (the linearity and the upper limit of the gain are limited by the power supply voltage, and the lower limit of the gain is limited by the DC offset of the op amp), Especially in wireless communication systems, the DC offset of the analog circuit will cause serious performance problems. In the transmitter, the DC offset of the analog circuit before the up-mixing circuit will cause the leakage of the local oscillator signal at the RF output terminal, destroying the error of the signal Vector magnitude (EVM); in the receiver, when the DC offset is severe, it will saturate and directly cause the receiver to fail

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