Video lectures from the iCS group @ IIT Madras

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

circuit_details [2014/09/10 19:28]
circuit_details [2014/09/10 19:28] (current)
Line 1: Line 1:
 +====== Circuit design details======
 +// [[ctsd_adc_90nm|go to project home]] //
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +===== ADC noise budgetting =====
 +  * For a dynamic range of 86dB, measured at -15dBFS input signal (at 85C)
 +
 +^ Noise source ^ noise spec ^ Noise referred to ADC i/p ^ %contribution|
 +^ Integrator1 Amp| 10 uV|20 uV|20%|
 +^ ADC i/p resistors| 23.3 uV|23.3 uV|30%|
 +^ DAC isource| 23.3 uV (referred to i/p resistors)|23.3 uV|30%|
 +^ Quantization| 96 dB |19 uV|20%|
 +
 +  * ADC i/p resistor is chosen to be 400 ohms single ended.
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +===== Integrator1 OTA =====
 +
 +
 +   ​* ​ Two different architectures are used to evaluate modulator performance with different mismatch-levels in the replica-o/​p-current sources. The summary of the results are given here --> {{:​updates_amp1_architecture.pdf?​800}}
 +   * **OTA1 architecture:​** 2-stage amplifier with cap-coupled feedforward compensation
 + ​{{:​amp1.png?​1000}}
 +   * ** Small-signal/​Noise performance **
 +
 +^ Parameter:​^worst value^worst corner (mos,​temp,​cap,​res)|
 +^ DC gain:|49.8 dB |SF_mos, 85C, min_cap |
 +^ UGB:|2.61 GHz |FS_mos, 85C, max_cap |
 +^ Phase Margin:​|48.3 degree |SS_mos, 85C, min_cap |
 +^ Amp i/p noise:|10.3 uV |SS_mos, 85C, min_cap |
 +
 +  * **Random Mismatch :** 
 +    * The o/p NMOS drain current is the most sensitive to random mismatch. The random current variation in the o/p NMOS transistor is under 10%.
 +    * The random current variation in the o/p PMOS transistor is under 3%.
 +
 +  * **Total supply current (OTA + bias)= 5.54mA**
 +  * ** SNDR performance : **
 +  * SNDR vs Replica matching (FF_mos, 85C, min_cap)
 +
 +^ replica matching :​^90%^95%^98%^100%^103%^105%^108%^110%|
 +^ SNDR for 100mV i/p signal:​|96.8 dB|97.7 dB|97.1 dB|96.2 dB|96.2 dB|97.5 dB| 97.6 dB|96.6 dB|
 +^ SNDR for 300mV i/p signal:​|94.6 dB |94.7 dB |96.2 dB|94.7 dB|94.7 dB|94.5 dB|95.4 dB|95.4 dB|
 +
 +  * SNDR across corners (10% replica matching)
 +
 +^ Parameter:​^worst value^worst corner (mos,​temp,​cap,​res)|
 +^ SNDR for 100mV i/p signal:​|95.7 dB |SF_mos, 85C, min_cap |
 +^ SNDR for 300mV i/p signal:​|94.1 ​ dB |FS_mos, 0C, min_cap |