Texas Instruments Corporation

Diptendu Ghosh

Rajarshi Mukhopadhyay

Siraj Akhtar

Reza Sharifi

Petteri Matti Litmanen

DAC design uses a passive reconstruction filter. The reconstruction filter includes a notch filter and series peaking filter. The notch filter provides notch filtering at the DAC clock frequency. The peaking filter increases signal bandwidth while attenuating frequency content at harmonics of the DAC clock frequency. The notch filter can be an LC notch filter with a notch inductor Ln and a notch capacitor Cn. The peaking filter can be a series peaking inductor Ls (shunted with a filter capacitor Cp). In a differential configuration, the passive reconstruction filter can be &#xb1;LC notch filters (with &#xb1;Ln notch inductors), and the peaking filter can be &#xb1;Ls peaking inductors coupled in series to the &#xb1;LC notch filters. The &#xb1;Ln notch inductors, &#xb1;Ls peaking inductors can be mutually wound as single inductors. For an example direct conversion RF transmit chain, IQ&#xb1; signal paths are implemented with differential DAC designs including passive reconstruction filters.

Digital to analog converter with passive reconstruction filter

Within hard disk drives (HDDs), for example, a preamplifier or preamp is generally used to perform read and write operations with a magnetic head. Typically, for write operations, the preamplifier generates a current waveform that uses a DC current to polarize magnetic elements within the disk and overshoot components to compensate for frequency dependent attenuation in the interconnect between the head and preamp. Conventional pulse-shaping circuitry used for this application uses high voltage to accomplish this task. Here, however, pulse-shaping circuitry is provided which can generate a similar waveform using lower voltage (i.e., about 5V) for this application and others.

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West Bengal, India

Diptendu Ghosh