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US 8,134,410 B1Granted
Transceiver gain calibration
AssigneePMC-Sierra, Inc.
InventorAnthony Eugene Zortea
Life of this patent
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Abstract
Transceivers with multiple gain stages that include open loop and closed loop amplifiers are subject to differential non-linearity (DNL) errors in their total gain versus gain index curve due to the gain step variability of the open loop amplifiers. The initial and time varying DNL can be reduced by a control loop that uses the relative gain step precision of the closed loop amplifiers and of passive attenuators to establish a control loop to reduce the DNL of the total gain.
Claims16
An apparatus having a controllable gain, the apparatus comprising:
- a first gain stage, wherein the first gain stage is configured to provide a first adjustable positive gain, wherein the first gain stage has a first step size for gain adjustment, wherein the first adjustable positive gain is adjustable at least to a first gain or a second gain, wherein the second gain is larger than the first gain;
- a second gain stage, wherein the second gain stage is configured to provide a second adjustable positive gain, wherein the second gain stage has a second step size that is less than half the size of the first step size for gain adjustment;
- an attenuator stage, wherein the attenuator stage is configured to provide adjustable loss, wherein the attenuator stage has a third step size smaller than the second step size for attenuation adjustment, wherein the first gain stage, the second gain stage, and the attenuator stage are cascaded in a forward signal path;
- and
- a control circuit configured to control gain of at least one of the first gain stage or the second gain stage for adjustment of at least a part of the total gain, wherein for at least one incremental adjustment of the total gain, the control circuit is configured to adjust the gains of the first gain stage and the second gain stage in opposite directions from each other and to adjust the attenuation of the attenuator stage to reduce differential non-linearity.
2 more elements
A method of reducing differential non-linearity (DNL) for cascaded gain stages having a controllable gain, the method comprising:
- controlling gain of at least one of a first gain stage or a second gain stage for adjustment of at least a part of a total gain, wherein the first gain stage, the second gain stage, and an attenuator stage are cascaded, wherein the first gain stage has a first step size for gain adjustment, wherein the second gain stage has a second step size that is less than half the size of the first step size for gain adjustment, wherein the attenuator stage has a third step size smaller than the second step size for attenuation adjustment;
- adjusting the gains of the first gain stage and the second gain stage in opposite directions from each other for at least one incremental adjustment of the total gain;
- and
- adjusting attenuation of the attenuator stage to reduce differential non-linearity for the at least one incremental adjustment with gains of the first gain stage and the second gain stage being adjusted in opposite directions;
- wherein controlling and adjusting are performed by electronic hardware.
2 more elements
An apparatus having a controllable gain, the apparatus comprising:
- a first gain stage, wherein the first gain stage is configured to provide a first adjustable positive gain, wherein the first gain stage has a first step size for gain adjustment, wherein the first adjustable positive gain is adjustable at least to a first gain or a second gain, wherein the second gain is larger than the first gain;
- a second gain stage, wherein the second gain stage is configured to provide a second adjustable positive gain, wherein the second gain stage has a second step size that is less than half the size of the first step size for gain adjustment;
- an attenuator stage, wherein the attenuator stage is configured to provide adjustable loss, wherein the attenuator stage has a third step size smaller than the second step size for attenuation adjustment, wherein the first gain stage, the second gain stage, and the attenuator stage are cascaded in a forward signal path;
- and
- means for controlling the gains of the first gain stage and the second gain stage in opposite directions from each other for at least one incremental adjustment of the total gain, and for adjusting attenuation of the attenuator stage to reduce differential non-linearity for the at least one incremental adjustment with gains of the first gain stage and the second gain stage being adjusted in opposite directions.
2 more elements
Dependencies are inferred from the claim text.