US 6,686,809 B2 · Filter trimming

Abstract

The invention relates to trimming of analogue filters (201) in integrated circuits by means of an automatic adjusting circuit. A local oscillator (202) in the automatic adjusting circuit provides a periodic reference signal (R) to an adjustable phase shifter (203), which on basis thereof, produces a periodic phase shifted signal (R*). A phase detector (204) receives both the periodic reference signal (R) and the phase shifted period signal (R*) and produces a test signal (T) in response to a phase difference between the periodic reference signal (R) and the periodic phase shifted signal (R8). A lowpass filter (205) receives the test signal (T) and generates a level signal (TDC) relative a reference level, e.g. representing a zero voltage. A digital signal processor (207) produces a primary control signal (CS), having a serial format, on basis of the observation signal (M). A serial-to-parallel converter (208) converts the primary control signal (CS) into a control signal (CP) having a parallel signal format. The control signal (CP) influences a magnitude of at least one component value in the adjustable phase shift between the periodic reference signal (R) and the periodic phase shifted signal (R*) attains a calibrated value being as close as possible to a desired value. A latch (210) forwards at least one signal element of the control signal (CP) for setting of at least one component value in the analogue filter (201) in accordance with a setting of at least one component value in the adjustable phase shifter (203) which produces the calibrated value.

Claims32

Dependent claims

A method for automatically altering a magnitude of at least one component value in an analog filter in an integrated circuit, the method involving:

receiving a periodic reference signal and a phase shifted periodic signal in a phase detector and producing a test signal in response to a phase difference between the periodic reference signal and the periodic phase shifted signal, characterised by
the integrated circuit comprising an adjustable phase shifter for receiving the periodic reference signal and on basis thereof producing the periodic phase shifted signal, the method further involving:
altering a magnitude of at least one component value in the adjustable phase shifter in response to a control signal, such that the phase difference between the signals attains a calibrated value which is as close as possible to a desired value, the control signal being generated on basis of the test signal, and
setting the at least one component value in the analog filter in accordance with setting of the at least one component value in the adjustable phase shifter which produces the calibrated value.

1 more element

An integrated circuit, comprising:

an adjustable phase shifter operable to receive a periodic reference signal and generate a periodic phase shifted signal;
a phase detector operable to identify a phase difference between the periodic reference signal and the periodic phase shifted signal;
a control signal generator operable to generate a control signal, the control signal associated with causing the adjustable phase shifter to adjust a magnitude of at least one component value in the adjustable phase shifter so that the phase difference attains a specified value;
and
an analog filter operable to adjust a magnitude of at least one component value in the filter based at least partially on the control signal.

2 more elements

A computer program loadable into the internal memory of a digital computer, comprising:

computer readable program code for identifying a phase difference between a periodic reference signal and a periodic phase shifted signal generated by an adjustable phase shifter;
computer readable program code for generating a control signal associated with causing the adjustable phase shifter to adjust a magnitude of at least one component value in the adjustable phase shifter so that the phase difference attains a specified value;
wherein the control signal is operable to cause an analog filter to adjust a magnitude of at least one component value in the analog filter.

Dependencies are inferred from the claim text.

Filter trimming

Life of this patent

Filter trimming

Life of this patent

Abstract

Claims32