Microsemi Corporation

Texas Instruments Corporation

Siliconsystems, Inc.

Yuji Isobe

Chii-Fa Chiou

Indumini W Ranmuthu

Yuji Yoshida

A power conversion circuit operates in a discontinuous switching mode over a wide range of loading conditions and varies a coil peak current to maintain efficiency over the wide range of loading conditions. The coil peak current is adjustable based at least in part on a feedback signal generated in response to a load condition.

Boost converter with adaptive coil peak current

A current-mode switching regulator uses a slope compensation circuit that automatically accounts for different inductor values and varying input voltages to generate a slope compensation signal. The slope compensation circuit monitors a voltage across a semiconductor switch to extract an upslope signal that tracks increasing inductor current in the current-mode switching regulator. The slope compensation signal is generated based on the upslope signal and a difference between an input voltage and an output voltage of the current-mode switching regulator.

Slope compensation circuit

A transimpedance amplifier uses a pseudo-differential configuration to improve dynamic range and to minimize signal distortion in an optical receiver. The optical receiver includes a photodiode that converts a light signal to an electrical current signal, and the transimpedance amplifier converts the electrical current signal to a pair of differential voltage signals for further processing. The electrical current signal is provided to the transimpedance amplifier by connecting a cathode of the photodiode to a first input amplifier via a DC-blocking capacitor and directly connecting an anode of the photodiode to a second input amplifier. The transimpedance amplifier includes a DC correction circuit that generates a correction current in response to an output of the first input amplifier. The correction current is added to an input of the second input amplifier to adjust a DC offset at an output of the second input amplifier.

Pseudo-differential transimpedance amplifier

A transimpedance amplifier selectively activates DC compensation to optimize a signal-to-noise ratio for an optical receiver. The optical receiver includes a photodiode that converts a light signal to an electrical current signal, and the transimpedance amplifier converts the electrical current signal to a pair of differential voltage signals for further processing. The electrical current signal is provided to the transimpedance amplifier by connecting a cathode of the photodiode to a first input amplifier via a DC blocking capacitor and by directly connecting an anode of the photodiode to a second input amplifier. The transimpedance amplifier includes a DC correction circuit that generates a correction current when an output of the first input amplifier exceeds a predefined threshold. The correction current is added to an input of the second input amplifier to adjust a DC offset at an output of the second input amplifier.

Transimpedance amplifier with selective DC compensation

A hard disk drive (HDD) circuit ( ) having feedback provided to an input of an differential amplifier setting the amplifier input impedance close to a flexible printed circuit (FPC) characteristic impedance. A matched source and input impedance produces a generally flat gain frequency response. As the result of flat response and wider gain bandwidth, white noise without high frequency peaking can be obtained. Feedback resistors (R ) provide feedback according to the present invention which is superior in terms of the input referred noise since the feedback attenuates both the input signal from the sensor and the noise from the amplifier. Feedback resistors (R ) may be connected through AC coupling capacitors to compensate the voltage differences between amplifier input and output. The circuit of the present invention provides a method to connect the feedback resistors directly from amplifier outputs to inputs which have a different potential. The advantages of the present invention include matched impedance results and a better system level frequency response, the direct feedback connection eliminates costly on-chip capacitors, and the input impedance can be adjusted by the amount of feedback.

Controlled impedance amplifiers

A differential circuit to read differential data from a disk by a voltage bias includes a read circuit to read the differential data from the disk by maintaining the voltage bias and a feedback circuit to sense deviations in the voltage and to adjust the voltage in response to the deviations.

Differential voltage bias, voltage sense preamplifier architecture

A cascode H-bridge circuit with particular application to magnetic recording write driver circuits. The present invention avoids the process dependent limitations placed on the head voltage swing in the H-bridge circuits of the prior art. Whereas the circuits of the prior art attempt to increase head voltage swing by minimizing device voltage drops in the current path, the present invention inserts cascode transistors in the current path that have less than a one-volt voltage drop when active, yet allow the circuit to operate under a higher voltage supply with roughly twice the head voltage swing available in the same process in the prior art. By implementing a cascode configuration, the present invention is able to support head voltage swings in excess of the switch breakdown voltage (BV ) without failure of the switches in the &ldquo;off&rdquo; state.

Self-switched cascode write driver

A write driver to operate inductive heads for magnetic recording is disclosed. The inductive recording head is coupled between first and second outputs of a first write driver block. The first and second outputs of the first write driver block are coupled to first and second inputs of a second write driver block, respectively. First and second current sources are coupled to third and fourth inputs of the second write driver block, respectively. A first switching block is coupled to the first current source and to the third input of the second write driver block. A second switching block is coupled to the second current source and to the fourth input of the second write driver block. A first input signal is provided to a first input of the first write driver block and to the first switching block. A second input signal is provided to a second input of the first write driver block and to the second switching block. The second output of the first write driver block, the inductive recording head and the first input of the second write driver block form a first current path when the first input signal is greater than the second input signal. Conversely, the first output of the first write driver block, the inductive recording head and the second input of the second write driver block form a second current path when the second input signal is greater. The first and second input signals may be CMOS or differential ECL signals.

Growing community of inventors

Irvine, CA, United States of America

Yuji Isobe