Apparatus and method for obtaining proper output signal in which gain and DC component are regulated based upon on measured amplitude distribution

• US 5,774,085 A
• Filed: 08/18/1997
• Issued: 06/30/1998
• Est. Priority Date: 09/14/1994
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Nakamura, Mitsuhiro, Yanagimoto, Yoshiyuki
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): JEAN PIERRE, PEGUY
• Application Number:
  US08/916,718
• Time in Patent Office: 316 Days
• Field of Search: 341/118, 341/120, 341/155
• US Class Current: 341/155
• CPC Class Codes: H03F 1/30 Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in differential amplifiers H03F3/45479
• CPC Class Codes: H03G 3/30 in amplifiers having semiconductor devices

Abstract

A circuit adjusts the gain, direct-current (DC) component, and transient response of input signals to provide suitable output signals for a connected signal processor. The circuit includes a gain and DC component control circuit, which controls the amplitude and DC offset level of an input signal; an A/D converter, which performs A/D conversion on the output of the gain and DC component control circuit; and an equalization filter, which is connected to the output of the A/D converter. The amplitude distribution of the output waveform of the equalization filter is measured, and the gain and DC component control circuit is controlled on the basis of said measured value, in order to assure that the output of the equalization filter is suitable for a connected signal processor.

Claims

1. A method comprising the steps of:

controlling a gain and direct-current component control circuit means to adjust amplitude and direct-current offset levels of an input signal;

performing A/D conversion on an output of said gain and direct-current component control circuit means to produce digital signals;

equalization filtering said digital signals to produce filtered digital signals;

measuring an amplitude distribution of said filtered digital signals by determining a measure of each digital signal, sorting into groups each said digital signal in accord with said measure thereof and determining a number of digital signals which fall into each group; and

controlling said gain and direct-current component control circuit means in dependence upon results of said measuring step to assure that said filtered digital signals exhibit a suitable signal characteristic which matches requirements of a connected signal processing means.

2. A method comprising the steps of:

controlling a gain and DC component control circuit means to adjust amplitude and DC offset levels of an input signal;

performing A/D conversion on an output of said gain and DC component control circuit means to produce digital signals;

equalization filtering said digital signals to produce filtered digital signals;

measuring an amplitude distribution of said filtered digital signals; and

controlling said gain and DC component control circuit means in dependence upon results of said measuring step to assure that said filtered digital signals exhibit a suitable signal characteristic which matches requirements of a connected signal processing means.

3. A device for receiving an input signal train including plural signals which exhibit plural logical signal levels that evidence a variability over multiple occurrences of said plural signals, said device comprising:

a) gain and direct-current (DC) component control circuit means for controlling an amplitude and DC offset level of said plural signals;

b) signal processing means for processing output signals corresponding to said plural signals from said gain and DC component control circuit means;

c) means for measuring amplitude distribution of logical signal levels of plural ones of said output signals from said gain and DC component control circuit means, said means for measuring sampling said plural signals, determining a measure of each sample, sorting into groups each said sample in accord with said measure thereof and determining a number of samples which fall into each group; and

d) means for controlling said gain and DC component control circuit means in dependence upon results of said measuring amplitude distribution so as to assure that said output from said gain and DC component control circuit means exhibits logical signal levels which match requirements of said signal processing means.

4. The device as recited in claim 3, wherein said means for controlling is connected to between said means for measuring amplitude distribution and said gain and DC component control circuit means and is automatically responsive to said results of said measuring amplitude distribution to provide control signals to said gain and DC component control circuit means.

5. A device for receiving an input signal train including plural signals which exhibit plural logical signal levels that evidence a variability over multiple occurrences of said plural signals, said device comprising:

a) gain and DC component control circuit means for controlling an amplitude and DC offset level of said plural signals;

b) an analog to digital (A/D) converter for performing A/D conversion of an output of said plural signals from said gain and DC component control circuit means;

c) signal processing means for processing of said plural signals from said A/D converter;

d) means for measuring amplitude distribution of logical signal levels of plural ones of said plural signals from said A/D converter, said means for measuring determining a measure of each sample from said A/D converter, sorting into groups each said sample in accord with said measure thereof and determining a number of samples which fall into each group; and

e) means for controlling said gain and DC component control circuit means in dependence upon results of said measuring amplitude distribution so as to assure that said logical signal levels that are output from said A/D converter match requirements of said signal processing means.