JAJSNF1A April 2022 – September 2022 PCM3120-Q1
PRODUCTION DATA
The device supports up to 12 programmable digital biquad filters. These highly efficient filters achieve the desired frequency response. In digital signal processing, a digital biquad filter is a second-order, recursive linear filter with two poles and two zeros. Equation 2 gives the transfer function of each biquad filter:
The frequency response for the biquad filter section with default coefficients is flat at a gain of 0 dB (all-pass filter). The host device can override the frequency response by programming the biquad coefficients to achieve the desired frequency response for a low-pass, high-pass, or any other desired frequency shaping. The programmable coefficients for the mixer operation are located in Section 8.6.4.1 and Section 8.6.4.2. If biquad filtering is required, then the host device must write these coefficients values before powering up any ADC channels for recording. As described in Table 8-19, these biquad filters can be allocated for each output channel based on the BIQUAD_CFG[1:0] register setting of P0_R108. By setting BIQUAD_CFG[1:0] to 2'b00, the biquad filtering for all record channels is disabled and the host device can choose this setting if no additional filtering is required for the system application. See the TLV320ADCx140 Programmable Biquad Filter Configuration and Applications application report for further details.
PROGRAMMABLE BIQUAD FILTER | RECORD OUTPUT CHANNEL ALLOCATION USING P0_R108_D[6:5] REGISTER SETTING | ||
---|---|---|---|
BIQUAD_CFG[1:0] = 2'b01 (1 Biquad per Channel) |
BIQUAD_CFG[1:0] = 2'b10 (Default) (2 Biquads per Channel) |
BIQUAD_CFG[1:0] = 2'b11 (3 Biquads per Channel) |
|
Biquad filter 1 | Allocated to output channel 1 | Allocated to output channel 1 | Allocated to output channel 1 |
Biquad filter 2 | Allocated to output channel 2 | Allocated to output channel 2 | Allocated to output channel 2 |
Biquad filter 3 | Allocated to output channel 3 | Allocated to output channel 3 | Allocated to output channel 3 |
Biquad filter 4 | Allocated to output channel 4 | Allocated to output channel 4 | Allocated to output channel 4 |
Biquad filter 5 | Not used | Allocated to output channel 1 | Allocated to output channel 1 |
Biquad filter 6 | Not used | Allocated to output channel 2 | Allocated to output channel 2 |
Biquad filter 7 | Not used | Allocated to output channel 3 | Allocated to output channel 3 |
Biquad filter 8 | Not used | Allocated to output channel 4 | Allocated to output channel 4 |
Biquad filter 9 | Not used | Not used | Allocated to output channel 1 |
Biquad filter 10 | Not used | Not used | Allocated to output channel 2 |
Biquad filter 11 | Not used | Not used | Allocated to output channel 3 |
Biquad filter 12 | Not used | Not used | Allocated to output channel 4 |
Table 8-20 shows the biquad filter coefficients mapping to the register space.
PROGRAMMABLE BIQUAD FILTER | BIQUAD FILTER COEFFICIENTS REGISTER MAPPING | PROGRAMMABLE BIQUAD FILTER | BIQUAD FILTER COEFFICIENTS REGISTER MAPPING |
---|---|---|---|
Biquad filter 1 | P2_R8-R27 | Biquad filter 7 | P3_R8-R27 |
Biquad filter 2 | P2_R28-R47 | Biquad filter 8 | P3_R28-R47 |
Biquad filter 3 | P2_R48-R67 | Biquad filter 9 | P3_R48-R67 |
Biquad filter 4 | P2_R68-R87 | Biquad filter 10 | P3_R68-R87 |
Biquad filter 5 | P2_R88-R107 | Biquad filter 11 | P3_R88-R107 |
Biquad filter 6 | P2_R108-R127 | Biquad filter 12 | P3_R108-R127 |