PCM1704の高性能化テクニック - tij.co.jp

1 Application Note JAJA006 WAS SBAA066. PCM1704 .. PCM1704 96kHz 8 . 768kHz . DAC PCM1702 768kHz 768kHz . PCM1704 .. fS = fS = 96kHz . 8 . PCM1704 . PCM1704 D/A 768kHz . 768kHz . DC 1fS 4fS . DC .. 1 of FSR 3 of FSR THD + N 0dB 20dB . FSR . DAC DLE . THD + N . 1 of FSR = 24mA THD . 3 of FSR J K 3 .. EIAJ . A 60dB. THD + N 60dB . THD + N DLE . S/N K . S/N A . DLE . 120dB S/N DAC . PCM1704 24 . 24 . 144dB DAC .. CD . 16 16 . 98dB DAC . 16 .. TA = +25 VCC = VDD = 5V fS = 768kHz = 24 . PCM1704U.. 24 Bits 20/24 MSB . 2's . fS 768 kHz 25 MHz . VIH(1) + + V. VIL(1) 0 + V. VIH(2) 0 V. VIL(2) V. IIH(1) VIH = VDD 10 A. IIL(1) VIL = 0V 10 A. IIH(2) VIH = 0V 10 A. IIL(2) VIL = VDD 100 A.. (3). THD + N VO = 0dB PCM1704U %. PCM1704U-J %. PCM1704U-K %. VO = 20dB PCM1704U %.

2 PCM1704U-J %. PCM1704U-K %. EIAJ A . PCM1704U U-J 102 110 dB. PCM1704U-K 106 112 dB. S/N EIAJ A 112 120 dB. f = 1002Hz at 90dB dB. DC . % of FSR. % of FSR. 0 +70 25 ppm of FSR/ . 0 +70 5 ppm of FSR/ .. mA. k . ( of FSR) (10 100 ) 200 nsec . : +VCC = +VDD + + + VDC. VCC = VDD VDC. : +ICC +VCC = +VDD = + 5 8 mA. ICC VCC = VDD = 30 45 mA.. 25 +85 . 55 +125 . 1 BCLK WCLK DATA 2 20 BIT INVERT 3 5534 I/V GIC3 LPF fc =. 48kHz . THD + N 725C. 400Hz HPF ON 30kHz LPF ON .. PCM1704 . BCLK DATA 768kHz 1 . PCM1704 24 . 24 . BCLK . 5V +VCC +VDD VCC VDD 24 768kHz = . IC .. 1 32 BCLK. 32 768kHz = PCM1704 . VCC . VDD . 25 MHz .. PCM1704 . 24 DATA . BCLK WCLK 1 PCM1704 . WCLK DAC fS = 8 24 . fS = 96kHz 8 PCM1704 . fS = 192kHz 4 . 768kHz . 2. 11. +VCC. 12. BPO. DC. +. + R-2R.

3 15,16. Bpo Amp 1. PCM1704 . AGND. BandGap 14. Reference R-2R. IOUT. 19 17. Q1 Q2. REF SERVO. DC DC. Servo Q3. Amp + +. Re 20. 3. VCC. 5. DGND. 6. +VDD Qa Qb Digital Portion Level Shift Switch Driver 1 Current Qc Source DATA. 2. BCLK.. 7 3 8 9 10 4. WCLK /TRIM /MODE /20bit /INV VDD. DAC 1 BPO .. IOUT .. 1 Q1 Q2 Q3 . 0 .. Re Re 1 / 2 D A C . GND .. IOUT Re BPO . V CC Q1 Q2 VCC . Qa Qb Qc VCC BPO . VDD GND . Q1 Q2 Q3 Re . Q1 Q2 . Qa Qb Qc . GND VCC. VDD . DAC TTL .. GND ON/OFF . VCC . VDD .. PCM1704 .. DAC .. I PCM1704 . I = V/R R V .. VCC Vb .. 2 PCM1704 . Vb VCC . +5V. +VDD +VCC. 2mA 3mA.. REF DC SRV DC. 0V DGND AGND 0V. + +. BPO BPO DC. +. 23 23 . IOUT.. DAC . 20mA 10mA. VDD VCC. 5V. 2. PCM1704 . 4. PCM1704 PCM1704. +VCC +VCC. AGND 5V AGND 5V . R. VCC VCC.

4 +VDD +VDD. DGND DGND. R. VDD VDD. 3. PCM1704 1 4. PCM1704 2 . +VCC +VDD VCC VDD . PCM1704. 5V . 3 . VDD. +VCC. VCC . AGND 5V . VCC. DAC 4 +VDD. DGND 5V .. VDD. 5V 1 . VDD . 5 . VCC .. DAC . ON/OFF 5. PCM1704 3 .. PCM1704 . VCC VCC VDD SR . DAC 1 .. I/V SR = dVO/dt t = 0 . PCM1704 DAC I/V = d f . /dt I/V = 106.. 29V/ s . 16 fS = .. I/V 24 fS = 96kHz I/. V . TS .. DAC I/V . DAC TS .. TS = 1/768kHz = s . DAC s . fS = 96kHz fS/2 = 48kHz . TS . 48kHz .. 48kHz .. TS . DAC 96kHz 8 = 768kHz . 16 . CD VO = 2 Vrms .. TS . 6 . s .. 5. 120dB . I/V 7 I/V .. DAC k . 100dB S/N . VS .. 2 fS A. 1/2TS = [1/(96kHz 8)] = 650nsec 2 (96kHz 8) 6 = s .. TS. of FSR. VS. TS TS TS TS. TS.. OPA134 20V/ s 1 s A : F/S signal swing at OPA627 55V/ s 550ns TS = 1/fS = 1/(96kHz 8) = sec 2 Vrms = 6V OPA604 25V/ s s 8 : 8.

5 6.. RO = 1K RF = Vno = (1 + RF /RO) Vni = Vni is specified as noise density, Vn / BW(Hz). Vn by OPA134 : 8nv/ BW(Hz). Vn by OPA627 : BW(Hz). Vn by OPA604 : 11nV/ BW(Hz).. BW = 20kHz, Vni . Vni (OPA134) : V. Vni (OPA627) : V. Vno Vni (OPA604) : V. +. Vno . Vno (OPA134) : V. Vno (OPA627) : V. Vni Vno (OPA604) : V. S(S = 2 Vrms) / N(Vno) (A ) . S/N (OPA134) : !! S/N (OPA627) : !! S/N (OPA604) : !! RO : PCM1704 . RF : I/V . Vni : . 7. I/V . 6. Root-Sum-Squares DAC . 7 . Root-Sum-Squares . S . 8 .. I/V . S1 S2 SO .. 20k SO = S1 + S2 = 2S S1 = S2 .. 2 Vrms S/N . A- . N1 N2 NO .. NO = . N12 + N22 . 120dB S/N . EIAJ S/N A- S N .. 20 Log 2/2 . = 3dB. n . DAC . n . HiFi DAC . S .. n DAC . THD +. THD + N THD DAC DLE . N = DAC DAC .. DLE .. THD + N . DAC Root-Sum-Squares.

6 DAC .. DAC . 9 DAC . DAC . 2 DAC PCM1704 . DAC .. S1. SOUT = S1 + S2 = 2S. N1. S2. NOUT = N12 + N22. N2. 8. Root-Sum-Squares . 7. 2 DAC . I/V .. G = . VO = 2 Vrms THD + N . DAC . BPO DAC . THD + N 0dB G = 1 . G = . 2dB. S/N DAC S/N DAC 114dB . 10 G = 1 . G = .. THD + N DAC 3dB 118dB . G = 1 VO = 4 Vrms .. 2 2 . S(1)rms + THD + N(1)rms PCM1704. SOUT + THD + NOUT. 2 . I/V. DATA . OPA627. OPA2134. PCM1704. S(2)rms + THD + N(2)rms THD + N n . SOUT = S(1)rms + S(2)rms = 2S [S(1) = S(2)] . THD + NOUT = THD + N(1)2 rms + THD + N(2)2 rms 2 (THD + N)2 rms n THD + N = as THD + N(1) = THD + N(2) THD + N(n) =. 2S rms n 9.. PCM1704 #1. (VOUT = 4 Vrms, G = 1). THD + N : : THD + N : SNR : : SNR : (VOUT = 2 Vrms, G = ). PCM1704 #2. THD + N : THD + N : : : SNR : SNR : 10.

7 8. THD + N THD . N .. 11 DAC . DAC . PCM1704 CMR . DAC 12 THD + N G = 1 . I/V 2 DAC G = . I/V I/V THD + N N .. 3dB . DAC S/N 5dB . CMR . CMR.. S(1)rms + THD + N(1)rms PCM1704 I/V. (INV) OPA627. SOUT + THD + NDOUT + NCM. Balanced 2 . DATA Ncm Amp . OPA2134 OPA2134. +. I/V. PCM1704. OPA627. S(2)rms + THD + N(2)rms CMRR . SOUT = S(2)rms [ S(1)rms] = 2 Srms [ S(1) = S(2)].. THD + NDOUT = THD + ND(2)2 rms + THD + ND(1)2 rms 2 (THD + ND)2 rms NCM n THD + ND = NCM = THD + ND(n) =. 2S rms CMRR n ND : NCM : CMRR : . 11.. PCM1704 #1. (VOUT = 4 Vrms, G = 1). THD + N : : THD + N : SNR : : SNR : . Balance Amp (OPA2134). +. (VOUT = 2 Vrms, G = ). PCM1704 #2. THD + N : THD + N : : : SNR : SNR : 12.. 9.. DAC . HiFi .. THD + N 14 PCM1704 20 SOP . S/N . IC . 15 16 .. 13 5.

8 4 DAC/ch 15 PCM1704. 8 DAC PCM1704 . DEM- PCM1704 .. DAC I/V .. 2 PCM1704 12.. DAC I/V .. PCM1704 .. I/V.. PCM1704 .. 2 .. IC IC . 1 DAC .. 2 .. 3 I/V .. 4 .. IC .. IOUT I/V . WCLK. CLOCK PCM1704. DATA (INV). I/V. OPA627. WCLK. CLOCK PCM1704.. DATA (INV). 24 8fS Balance Amp (OPA2134) . WCLK. +. CLOCK PCM1704. DATA. I/V. OPA627. WCLK. CLOCK PCM1704. DATA. 13.. 10. Important 5V.. 1. DATA. BCLK. WCLK. Important IOUT. GND pin Top layer Bottom layer 10. Bypass CAP. +5V. 14. PCM1704 . Top layer ( ) . 5V line GND. PCM1704U. +5V line IOUT. I/V. Bottom layer : ( 1 ). 15. DEM-PCM1704 . ( ANJ1092).. TIJ TI . Texas Instruments Incorporated TIJ TIJ . Texas Instruments Incorporated TI TI . TI .. TI TI TI .. TI TI .. TI TI . TI . TI .. TI . TI TI .. TI TI .. TI TI.

9 TI .. TI .. TI TI . TI . Copyright 2006, Texas Instruments Incorporated .. / 3.. 4.. 1.. 5.. 260 10.. 6.. 2.. 0 40 40 85.