Abstract: A signal generator circuit for reducing power consumption of out-of-band message communications between a first device including the signal generator circuit and a second device coupled to the first device comprises a switching circuit and a controller coupled to the switching circuit. The controller is operative to receive a reference clock signal and at least a first control signal indicative of a request for the first device to send a message to the second device when the first device is in a first mode of operation. The controller generates an output control signal and an output data signal. The output control signal is operative as a function of the first control signal to selectively power up the switching circuit and a transmitter driver during the first mode. The output data signal includes the message supplied to the transmitter driver for transmission to the second device during the first mode.

Abstract: A signal generator circuit for reducing power consumption of message communications between a first device including the signal generator circuit and a second device coupled to the first device comprises a switching circuit and a controller coupled to the switching circuit. The controller is operative to receive a reference clock signal, to receive at least a first control signal indicative of a request for the first device to send a message to the second device when the first device is in a first mode of operation, and to generate an output control signal and an output data signal. The output control signal is operative as a function of the first control signal to selectively power up the switching circuit and a transmitter driver during the first mode. The output data signal includes the message supplied to the transmitter driver, via the switching circuit, for transmission to the second device during the first mode.

Abstract: The present invention is a method, system, and product for testing operating characteristics of a continuous-time or discrete-time device under test, which is included within a circuit. The operating characteristics of the continuous-time or discrete-time device are tested utilizing electronic components that already exist within the circuit such that a test circuit is not utilized to test the device. The circuit includes a variable gain amplifier and an automatic gain correction (AGC) circuit. The operating characteristics of the device are tested utilizing the variable gain amplifier and said AGC circuit.

Abstract: The present invention is a method, system, and product for testing operating characteristics of a continuous-time or discrete-time device under test, which is included within a circuit. The operating characteristics of the continuous-time or discrete-time device are tested utilizing electronic components that already exist within the circuit such that a test circuit is not utilized to test the device. The circuit includes a variable gain amplifier and an automatic gain correction (AGC) circuit. The operating characteristics of the device are tested utilizing the variable gain amplifier and said AGC circuit.

Abstract: An apparatus and method for estimating an amplitude of a readback signal obtained from a data storage medium and input to a gain modifying amplifier involves sensing an amplifier output signal in response to a readback signal applied to the amplifier. An amplifier control signal is produced which is representative of a difference between the amplifier output signal and a reference signal. A compensation signal associated with a temperature coefficient of amplifier gain is generated, and an estimate signal indicative of the amplitude of the readback signal is produced using the compensation signal. The estimate signal is representative of readback signal amplitude when the estimate signal has a magnitude equivalent to that of the difference signal and a polarity opposite that of the difference signal.

Abstract: A method for measuring an amplitude of a readback signal obtained from a data storage medium involves transmitting the readback signal to a gain modifying amplifier, such as a variable gain amplifier (VGA), preferably provided in the read channel. A voltage signal associated with a loop gain of the amplification circuitry is sensed and compared with a number of control voltage signals, each of the control voltage signals being associated with a corresponding digital word value. The digital word value associated with a control voltage signal that is equal to the sensed voltage signal represents the relative amplitude of the readback signal. Gain characterization circuitry may further be combined with readback signal amplitude measuring circuitry, preferably in-situ a read channel, to obtain the absolute amplitude of a readback signal.

Abstract: A circuit arrangement and method vary in response to temperature changes the signal swing of an input signal to an analog circuit which has a temperature-dependent effective linear signal range. A variable gain circuit varies the signal swing of the input signal in response to a control signal supplied thereto by a temperature control circuit so that the signal swing tracks changes in the effective linear signal range of the analog circuit. In this manner, signal to noise ratio may be optimized and distortion may be minimized over a range of operating temperatures for the analog circuit.

Abstract: An improved method and apparatus are provided for dc offset trim adjustment of a variable gain amplifier. The VGA has predetermined overall gain endpoints. A minimum gain and a maximum gain are identified for the VGA in a preferred operational range. The identified minimum gain and the identified maximum gain for the VGA in the preferred operational range are spaced apart inwardly from the VGA predetermined overall gain endpoints. The minimum gain for the VGA in operation is set, then trim adjustment of the VGA is provided to minimize an output of the VGA. Then the maximum gain for the VGA in operation is set, then dc offset trim adjustment of the VGA is provided to minimize an output of the VGA.