International Business Machines Corporation

Philip J Murfet

James Stephen Mason

Gareth John Nicholls

Thomas J Bardsley

Matthew R Cordrey-Gale

Louis L Hsu

Christopher N Wallis

Hayden C Cranford, Jr

Louis Lu-Chen Hsu

Li-Kong Wang

Michael Anthony Sorna

Karl David Selander

Michael John Palmer

Huihao Xu

Samuel Taylor Ray

Adrian C Lee

Thomas Winlow

Matt R Cordrey-Gale

Gareth J Nickolls

Stephen Furniss

A method of varying the gain of an amplifier and an amplifier array are provided. The amplifier array includes two or more amplifier stages () connected in parallel with each amplifier stage having a gain control means. Input signal means () are provided for each amplifier stage with the input signals of the amplifier stages being of different amplitude. Means for enabling and disabling an amplifier stage () are provided and means for summing the outputs of the enabled amplifier stages obtain an output signal (). The gain of the amplifier array has a range from a low gain setting with a first amplifier stage () enabled, through increasing gain settings as the gain of the first amplifier stage is increased from a minimum to a maximum gain, a second amplifier stage () can then be enabled in addition to the first amplifier stage and the gain of the second amplifier stage increased from a minimum to a maximum gain, further amplifier stages are enabled as available up to a maximum gain setting for the amplifier array. Each amplifier stage that is enabled has a decreasingly attenuated input signal and a final amplifier stage to be enabled has a full input signal ().

Variable gain amplifier

A CMOS receiver system having a tunable receiver having a tunable gain and a bandwidth system is provided. The tunable receiver includes means for receiving input signals; and a control circuit controlled by a control signal for tuning at least one of the gain and the bandwidth of the tunable receiver, wherein the control signal is indicative of a data rate of the input signals. Furthermore, a method is provided for tuning a CMOS receiver receiving input signals. The method includes the steps of receiving at least one control signal, and controlling one of gain and bandwidth of the CMOS receiver in accordance with the at least one control signal, wherein the at least one control signal is indicative of a data rate of the received input signals.

Tunable CMOS receiver apparatus

A data receiver is provided which includes a front end interface circuit having an alternating current (AC) transmission receiving mode and a direct current (DC) transmission receiving mode. The front end interface circuit includes an offset compensation circuit operable to compensate a DC voltage offset between a pair of differential signals input to the data receiver. The front end interface circuit further includes an AC/DC selection unit operable to switch between (a) the DC transmission receiving mode, and (b) the AC transmission receiving mode, such that the data receiver is operable in (i) the DC transmission mode in which the offset compensation circuit is disabled, (ii) the DC transmission mode in which the offset compensation circuit is enabled, (iii) the AC transmission mode in which the offset compensation circuit is disabled, and (iv) the AC transmission receiving mode in which the offset compensation circuit is enabled.

Front end interface for data receiver

Described is a system for trimming the value of an electronic component. The system comprises: at least one trimming component, each trimming component having an associated switch for selectively connecting that trimming component to the electronic component in response to a corresponding bit in a control vector. A comparator is included for generating an output bit having a first value if a net value of the electronic component and any connected trimming components differs from a desired value. A controller connected to the switches and the comparator generates the control vector in dependence on the output of comparator, the controller comprising a shift register for sequentially receiving successive output bits from the comparator; wherein the control vector comprises the contents of the shift register and wherein a bit of said first value in control vector effects switching of the corresponding switch.

Electronic component value trimming systems

An asynchronous serial data receiver utilizes plural samples of each data bit in a word to assure detection and reading of the midpoint of each bit to mitigate problems associated with noise and mismatches between the data and sampling rates. To this end, a shift register having plural stages for each bit samples the data stream at a clock rate which is a multiple of the data rate which provides multiple samples of each incoming bit. When the data word is fully read into the shift register the start bit is detected and initiates a parallel transfer of the data word using bit values taken from the midpoint of each bit period.

Asynchronous serial data receiver with capability for sampling the

An asynchronous serial data receiver for receiving a stream of data bits, characterized by a plurality of shift registers (54) into which samples corresponding to points within said data bit stream are read, different shift registers (54) holding a different set of said samples, said points being separated by most one half of a data bit period, and a decoder (60-90) responsive to said samples held in said shift registers (54) for recognizing points of known phase within said data assessed relative to which samples which corresponding to points within said data bits may be identified for reading. The invention provides a high speed serial receiver which is particularly suitable for use within disc drives and data storage and retrieval systems in general. The serial data receiver of the present invention does not require a clock synchronized with the incoming data. Furthermore the serial data receiver is able to share the sampling of the data bit stream between a plurality of shift registers (54) none of which need be clock more than once per data bit period.

Serial data receiver with phase shift detection

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Stockbridge, United Kingdom

Philip J Murfet