Abstract: An amplifier apparatus having a gain programmable in discrete increments includes: (a) an operational amplifier having a first and second input and an output; (b) a feedback circuit between the output and the second input; (c) a reference signal source and supply circuit coupled with the first input; (d) a first resistor network coupled between a first signal locus and the first input conveying a first input signal to the first input and including a first plurality of parallel-connected first resistors; selected first resistors being independently coupled in a first connecting with the first input; (e) a second resistor network coupled between a second signal locus and the second input conveying a second input signal to the second input and including a second plurality of parallel-connected second resistors; selected second resistors being independently coupled in a second connecting with the second input.

Abstract: A clamping circuit disclosed herein has two modes of operation which include both a bottom level and mid-level clamping mode for clamping automatically onto the sync tip of a video signal and customizably clamping onto the front porch, back porch/pedestal or anywhere within the signal. The clamping circuit (400) includes a clamping capacitor (404) that couples to an automatic clamping circuit portion (405) to automatically clamp the synchronization pulse of the video input signal to a first predetermined reference voltage (Vref1) of a first clamping pulse signal during an automatic clamping mode of operation. The automatic clamping portion (405) connects to the customizable clamping circuit portion (411) to clamp any portion of the video input signal to a second predetermined reference voltage (Vref2) of a second clamping pulse signal during a customizable clamping mode of operation. A buffer (416) connects between the customizable clamping circuit portion and the output node of the clamping circuit.

Abstract: 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 (300a-300b) may include a capacitive switching circuit (304a-304b), a capacitive switching circuit (306a-306b), and an operational amplifier (302a-302b). Capacitive switching circuits (304a-304b and 306a-306b) may receive an analog input voltage through sample switches (308a-308b and 310a-310b). Capacitive switching circuit (304a-304b) receives an output from operational amplifier (302a-302b) through feedback switch (312a-312b). The programmable gain amplifier (300a-300b) 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.

Abstract: An image processing apparatus (200) 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 (202, 204, 206, 208, 210) to sample the incoming optical black signal output from a CCD. This first circuit includes a correlated double sampler (202) coupled to a first programmable gain amplifier (204). An adder (206) connects between the first programmable gain amplifier (204) and a second gain amplifier (208) for adding in the optical black offset to the optical black signal input from the CCD. A second circuit (212, 214) includes a reverse programmable gain amplifier (212) connected to the output of the second programmable gain amplifier (208) to amplify the optical black level inversely proportional to the gain from the second programmable gain amplifier (208).

Abstract: An amplifier apparatus having a gain programmable in discrete increments includes: (a) an operational amplifier having a first and second input and an output; (b) a feedback circuit between the output and the second input; (c) a reference signal source and supply circuit coupled with the first input; (d) a first resistor network coupled between a first signal locus and the first input conveying a first input signal to the first input and including a first plurality of parallel-connected first resistors; selected first resistors being independently coupled in a first connecting with the first input; (e) a second resistor network coupled between a second signal locus and the second input conveying a second input signal to the second input and including a second plurality of parallel-connected second resistors; selected second resistors being independently coupled in a second connecting with the second input.

Abstract: An apparatus, system and method for clamping a video signal input to a coupling capacitor (215) for providing a clamping voltage. A charging current is applied to the capacitor (215) via an amplifier (225) having a first input (227) coupled with the capacitor output and a second input (226) coupled to a reference potential, the amplifier (225) is responsive to the capacitor output signal and the reference potential for providing the charging current to the capacitor (215). The current has a linearly varying magnitude which is proportional to a difference between the capacitor output and the reference potential.

Abstract: An image processing apparatus (800) for a charge coupled device having hot/cold pixel and line noise filtering is disclosed which provides optical black and offset correction. The present invention teaches an offset and optical black correction circuit having a digital filter to obtain noise-free optical black correction for charge-coupled devices such that a digitally programmable bandwidth exists. The sum of the channel offset and optical black level is averaged for a given number of lines having a number of optical black cells per line and this sum passes through a digital filter. Moreover, the channel is digitally calibrated to obtain a user programmed ADC (810) output which corresponds to that average.

Abstract: An image processing apparatus for a charge coupled device including analog front end circuitry having optical black and offset correction, whereby the an offset and optical black correction circuit has a digitally programmable bandwidth is disclosed herein. The image processing apparatus includes a sampling circuit to sample the incoming optical black signal output from a CCD. The sampled signal is filtered through an analog-to-digital converter for processing by a digital detector circuit which detects the average optical black level of the sampled signal. The sum of the channel offset and optical black level present at the output of the digital detector circuit as a digital error signal is averaged for a given number of lines and optical black cells per line by a digital averager included within the digital detector circuit. Moreover, calibration logic digitally calibrates the channel to obtain a user programmed ADC output which corresponds to that average.

Abstract: A shunt-shunt feedback current to voltage converter (60) including a compensating current (22) provided to the output of the amplifier (12) which mirrors the input current (14) advantageously removing the loading effects of the feedback resistor (Rf) to the amplifier (12). A current steering DAC (40) is utilized in conjunction with a plurality of polarity control switches (62) to provide either a source current or a sink current to the amplifier input, and a complementary sink current or source current, respectively, to the output of the amplifier such that the amplifier (12) does not provide any current to the feedback resistor. Thus, DC gain of the amplifier is maintained. The current steering DAC (40) provides a matched source current and sink current to achieve this architecture.

Abstract: An image processing apparatus for charge coupled device (CCD) and video inputs in a digital camera or for a digital camcorder is disclosed which provides optical black and offset correction for CCD inputs. A sampling circuit, including correlated double sampler (CDS) (402) and programmable gain amplifier (450), samples the image input signal and the video input signal. CDS (402) includes a single-ended amplifier (404) and a differential amplifier (406). The single-ended amplifier (404) functions such that it is only operable during an CCD signal input; otherwise, the single-ended amplifier (404) is bypassed such that a video signal is only sampled by the differential amplifier (406). For CCD signals, the single-ended amplifier (404) samples the reference level of the pixel and holds it during the video interval. The differential amplifier (404) samples both the output of the single ended amplifier (404) and the video level of the same pixel.

Abstract: An apparatus for providing optical black and offset calibration for an array signal comprising a sequence of voltage levels corresponding to a sequence of voltage samples of charge coupled devices arranged in an array. The apparatus includes a correlated double sampler adapted to receive the array signal and provide as an output a modified array signal comprising a sequence of first corrected output voltage levels. A programmable gain amplifier receives the modified array signal and provides as an output an amplified modified array signal comprising a sequence of second corrected output voltage levels. An analog to digital converter receives the amplified modified array signal and provides as an output a sequence of digital values. A digital signal storage device stores a digital value corresponding to a desired optical black level.

Abstract: A clamping circuit disclosed herein has two modes of operation which include both a bottom level and mid-level clamping mode for clamping automatically onto the sync tip of a video signal and customizably clamping onto the front porch, back porch/pedestal or anywhere within the signal. The clamping circuit (400) includes a clamping capacitor (404) that couples to an automatic clamping circuit portion (405) to automatically clamp the synchronization pulse of the video input signal to a first predetermined reference voltage (Vref1) of a first clamping pulse signal during an automatic clamping mode of operation. The automatic clamping portion (405) connects to the customizable clamping circuit portion (411) to clamp any portion of the video input signal to a second predetermined reference voltage (Vref2) of a second clamping pulse signal during a customizable clamping mode of operation. A buffer (416) connects between the customizable clamping circuit portion and the output node of the clamping circuit.

Abstract: A shunt-shunt feedback current to voltage converter (60) including a compensating current (22) provided to the output of the amplifier (12) which mirrors the input current (14) advantageously removing the loading effects of the feedback resistor (Rƒ) to the amplifier (12). A current steering DAC (40) is utilized in conjunction with a plurality of polarity control switches (62) to provide either a source current or a sink current to the amplifier input, and a complementary sink current or source current, respectively, to the output of the amplifier such that the amplifier (12) does not provide any current to the feedback resistor. Thus, DC gain of the amplifier is maintained. The current steering DAC (40) provides a matched source current and sink current to achieve this architecture.

Abstract: 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 (300a-300b) may include a capacitive switching circuit (304a-304b), a capacitive switching circuit (306a-306b), and an operational amplifier (302a-302b). Capacitive switching circuits (304a-304b and 306a-306b) may receive an analog input voltage through sample switches (308a-308b and 310a-310b). Capacitive switching circuit (304a-304b) receives an output from operational amplifier (302a-302b) through feedback switch (312a-312b). The programmable gain amplifier (300a-300b) 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.

Abstract: 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 (300a-300b) may include a capacitive switching circuit (304a-304b), a capacitive switching circuit (306a-306b), and an operational amplifier (302a-302b). Capacitive switching circuits (304a-304b and 306a-306b) may receive an analog input voltage through sample switches (308a-308b and 310a-310b). Capacitive switching circuit (304a-304b) receives an output from operational amplifier (302a-302b) through feedback switch (312a-312b). The programmable gain amplifier (300a-300b) 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.

Abstract: 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 (300a-300b) may include a capacitive switching circuit (304a-304b), a capacitive switching circuit (306a-306b), and an operational amplifier (302a-302b). Capacitive switching circuits (304a-304b and 306a-306b) may receive an analog input voltage through sample switches (308a-308b and 310a-310b). Capacitive switching circuit (304a-304b) receives an output from operational amplifier (302a-302b) through feedback switch (312a-312b). The programmable gain amplifier (300a-300b) 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.

Abstract: A CMOS programmable gain amplifier (10) is disclosed which provides exponential gain using a single gain element (19) which may be implemented in either bipolar or CMOS technology. An embodiment of the present invention includes a first and second sampling impedance (12, 14), a first and second feedback impedance (16, 18) and a gain element (19). The gain element (19) having an inverting input, a non-inverting input and an output. The inverting input connects to the first sampling impedance (12). The non-inverting input connects to the second sampling impedance (14). The first feedback impedance (16) connects between the inverting input and the output. The second feedback impedance (18) connects between the non-inverting input and the output.

Abstract: An image processing apparatus (200) 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 (202, 204, 206, 208, 210) to sample the incoming optical black signal output from a CCD. This first circuit includes a correlated double sampler (202) coupled to a first programmable gain amplifier (204). An adder (206) connects between the first programmable gain amplifier (204) and a second gain amplifier (208) for adding in the optical black offset to the optical black signal input from the CCD. A second circuit (212, 214) includes a reverse programmable gain amplifier (212) connected to the output of the second programmable gain amplifier (208) to amplify the optical black level inversely proportional to the gain from the second programmable gain amplifier (208).