Texas Instruments Corporation

Yong Han

Haydar Bilhan

Feng Ying

Gary Lee

Ching-Yuh Tsay

M C Ramesh

Indumini W Ranmuthu

Davy H Choi

Gonggui Xu

Sami Kiriaki

Ramesh Chandrasekaran

Lieyi Fang

An image processing apparatus () for a charge coupled device including analog front end circuitry having optical black and offset correction, whereby the offset and optical black correction circuit is programmable. The present invention includes a first circuit () to sample the incoming optical black signal output from a CCD. This first circuit includes a correlated double sampler () coupled to a first programmable gain amplifier (). An adder () connects between the first programmable gain amplifier () and a second gain amplifier () for adding in the optical black offset to the optical black signal input from the CCD. A second circuit () includes a reverse programmable gain amplifier () connected to the output of the second programmable gain amplifier () to amplify the optical black level inversely proportional to the gain from the second programmable gain amplifier (). The second circuit () also includes an integrator () coupled to the reverse programmable gain amplifier () to integrate the difference between the incoming signal and the desired optical black value. The second circuit () couples to the adder () to add the positive and negative difference to the optical black signal. An analog-to-digital converter () converts the sampled signal for further processing at the output of the image processing apparatus ().

Analog optical black clamping circuit for a charge coupled device having wide programmable gain range

A programmable gain amplifier using metal-oxide-semiconductor (MOS) devices to approximate exponential gain characteristic with linear control signals is disclosed. According to one embodiment, the programmable gain amplifier () may include a capacitive switching circuit (), a capacitive switching circuit (), and an operational amplifier (). Capacitive switching circuits (and) may receive an analog input voltage through sample switches (and). Capacitive switching circuit () receives an output from operational amplifier () through feedback switch (). The programmable gain amplifier () may include a few additional unit capacitors which can allow larger gain ranges or more steps for a given range without a large increase in chip size.

Method and apparatus for exponential gain variations with a linearly varying input code

A programmable gain amplifier using metal-oxide-semiconductor (MOS) devices to approximate exponential gain characteristic with linear control signals is disclosed. According to one embodiment, the programmable gain amplifier ( ) may include a capacitive switching circuit ( ), a capacitive switching circuit ( ), and an operational amplifier ( ). Capacitive switching circuits ( and ) may receive an analog input voltage through sample switches ( and ). Capacitive switching circuit ( ) receives an output from operational amplifier ( ) through feedback switch ( ). The programmable gain amplifier ( ) may include a few additional unit capacitors which can allow larger gain ranges or more steps for a given range without a large increase in chip size.

Preamplifiers are used in hard disk drive applications to read data stored on magnetic disk. Current bias current sense preamplifiers have a problem with bandwidth rolloff due to relatively high inductance. Voltage sense preamplifiers have a problem with peaking due to input capacitance. An improved current bias voltage sense preamplifier inserts a PMOS transistor M between the Rmr head and the bipolar transistor Q . The PMOS transistor M and the bipolar transistor Q form a high impedance voltage sense preamplifier. Biasing of the MR head is performed transistors M and M that mirror the current supplied by the current digital to analog converter into the MR head. Hence, the preamplifier is also of the current bias type. Peaking is controlled through a programmable current in an input capacitance cancellation circuit

Current bias voltage sense single ended preamplifier

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Plano, TX, United States of America

Yong Han