| 摘要 |
PURPOSE: A digital filter tuning circuit capable of analog compensation is provided to maintain a constant transconductance by performing analog compensation for a variation on a source voltage and a chip temperature. CONSTITUTION: A digital filter tuning circuit capable of analog compensation includes a master filter(10), a slave filter(20), a frequency comparator(30), a digital code generator(40), and a D/A converter(50). The digital filter tuning circuit further includes a transconductance conversion cell(60), and a voltage comparator(70). The slave filter operates as a continuous time filter. The frequency comparator compares a frequency signal with a reference clock frequency. The transconductance conversion cell receives an analog voltage signal from the D/A converter and generates a voltage signal which is Gm(transconductance) compensated based on a feedback signal of a Gm adjustment voltage. The voltage comparator compares the voltage signal from the transconductance conversion cell with a specific output voltage signal and generates the Gm adjustment voltage which equalize the received voltage signal with the specific output voltage signal. |
