US 6,184,752 B2Granted

Amplifier device with digitally controllable gain and optical disc read apparatus incorporating such a device

AssigneeThomson multimedia S.A.

InventorPierre Dautriche

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Abstract

The device has reference current sources (T71, T72, T7M) which are arranged in such a way that the sum of the currents flowing through each of the said sources is equal to the input current (IIN, I′IN) and output current sources (T81, T82, T8N), in each of which the current flowing through the reference sources is duplicated and which are arranged in such a way that the sum of the currents flowing through the output sources is equal to the output current (IOUT, I′OUT). The number of reference sources (T71, T72, T7M) and output sources (T81, T82, T8N) which are connected is controlled by the digital signal (200) and determines the gain of the device. Application to the circuit for processing the signals output by a read head of an optical disc reader apparatus.

Claims9

Dependent claims

A variable-gain amplifier device receiving an input signal and being controlled by a digital signal, comprises:

an input stage for converting the input signal into an input current;
a first series of reference current sources which are arranged in such a way that the sum of the currents flowing through each of said reference sources is equal to the input current;
a second series of output current sources, in each of which the current flowing through the first reference sources is duplicated and which are arranged in such a way that the sum of the currents flowing through the output sources is equal to the output current;
an output stage for converting the output current into an output signal;
wherein the number of sources which are connected in the first and second series of current sources is controlled by said digital signal and determines the gain of said device.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/413,393Filed 6 Oct 1999
Priority: FR 98 124956 Oct 1998
Granted: 6 Feb 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H03G 1/0088
Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal: using discontinuously variable…
G11B 7/005
Recording, reproducing or erasing methods; Read, write or erase circuits therefor: reproducing
G11B 7/0941
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…
H03G
Control of amplification