Principal and subordinate structure frequency calibration circuit used for Gm-C filter

Abstract

The invention discloses a principal and subordinate structure frequency calibration circuit used for a Gm-C filter. The principal and subordinate structure frequency calibration circuit used for the Gm-C filter comprises a transconductance amplifier principal and subordinate structure control circuit, an RC oscillating circuit and a digital logic circuit, wherein a principal transconductance amplifier in the principal and subordinate structure control circuit and a subordinate transconductance amplifier inside the Gm-C filter are matched and are controlled through the same bias voltage, so that the transconductance value Gm and the resistance R in the principal and subordinate structure control circuit are in accurate inverse relation; influence on the frequency by errors of the transconductance amplifier process is converted to be influence on the frequency by the errors of the resistance process. Compared with a traditional frequency calibration circuit for the Gm-C filter, the principal and subordinate structure frequency calibration circuit used for the Gm-C filter has the advantages of being simple in structure and good in robustness.

Description

technical field [0001] The invention relates to a master-slave structure frequency calibration circuit for Gm-C filter. Background technique [0002] The calibration circuit is an essential module in the integrated filter circuit. With the development of semiconductor integrated circuits, analog and digital single chips are becoming more and more mainstream. Low-IF filters, as key circuits for radio frequency transceivers and sensor interfaces, are often selected to be integrated on chips to reduce system size and cost. and improve system performance. However, due to process factors such as manufacturing tolerances, process changes, and device aging, the frequency characteristics of the filter will change greatly. For example, a process deviation of 20% in resistors and capacitors will cause a 30% to 50% error in filter frequency. The solution is to add a frequency calibration circuit in the integrated filter, and adjust the parameters of the device adaptively, so that th...

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Problems solved by technology

However, several modules of this calibration circuit need to consume a lot of power consumption, and at the same time, the voltage-controlled oscillator still has limitations and stability problems.

[0004] The master-slave control idea of ​​the transconductance amplifier first appeared in the variable gain amplifier. To achieve high-precision gain adjustment, the variable gain amplifier requires high accuracy of the transconductance value of the transconductance amplifier. The transconductance of the transconductance amplifier The value is usually related to multiple device parameters, and it is also a simple linear correlation, so it is difficult to achieve high precision by direct regulation

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