Broadband program control phase shift circuit based on programmable attenuator

Abstract

The invention relates to a high-stability broadband program control phase shift circuit based on a programmable attenuator. The system comprises a phase-shifting network and a programmable low-pass filter based on a programmable attenuator. Compared with a traditional program-controlled phase-shifting circuit based on a voltage-controlled gain amplifier, the program-controlled phase-shifting circuit has the advantages of being large in working frequency bandwidth, high in phase-shifting precision, small in output waveform noise, small in distortion, stable, not prone to self-excitation and the like.

Description

technical field [0001] The invention relates to a program-controlled phase shifter system, in particular to a broadband program-controlled phase-shift circuit based on a programmable attenuator. Background technique [0002] In fields such as radio frequency communication and analog electronics, phase shifting technology has been widely used. Through the phase shifting technology, various functions such as quadrature modulation and phased array can be completed. [0003] Many phase shifting applications involve fixed or controllable phase shifting within a certain frequency range, while traditional phase shifting networks move different phases for different frequency points. Therefore, it is necessary to dynamically change the parameters of the phase-shifting network when the circuit is working in order to achieve a controllable phase shift. [0004] The low-frequency program-controlled phase shifter can convert the analog signal into the digital domain through ADC samplin...

AI Technical Summary

Problems solved by technology

However, there are some disadvantages when using a voltage-controlled gain amplifier: 1) It is necessary to use a DAC to generate a DC control voltage to adjust the gain of the voltage-controlled amplifier, which increases the complexity of the circuit

2) The input and output dynamic range of this type of voltage-controlled gain amplifier is not large enough (for example, the maximum swing of the output signal of VCA810 generally does not exceed 3V peak-to-peak, if VCA821 is used, the dynamic range of the input signal is limited by the external gain resistor, generally is not large enough), so the phase adjustment range of the program-controlled phase shifter circuit in the actual measurement cannot reach the theoretical calculation value, and the phenomenon of output waveform distortion is prone to occur

3) The voltage-controlled gain amplifier has certain restrictions on the ripple and noise of the DC control voltage. During the actual test, it was found that the programmable phase shifter circuit using the voltage-controlled gain amplifier as the controllable gain unit sometimes has self-excited Oscillation, sometimes the output waveform will generate relatively large noise

4) The gain control bandwidth or the dynamic range of the input and output signals is small. The gain control bandwidth of the voltage-controlled gain amplifier chip VCA810 is about 25MHz. If the voltage-controlled gain amplifier chip VCA821 is used, the bandwidth can exceed 100MHz, but the gain control range is generally only 40dB

Images