Other Parts Discussed in Thread: ADS1271, OPA2140, REF5025, LM4140, REF2030
Dear All,
In one of my application has very low noise budget. I am using REF2025 as reference to INA and 24-Bit ADC.
The input to INA is in the range of 50uV to 1mV roughly.
I am getting ~ 30 uVp-p noise in my ADC counts. After oversampling and doing the average of 1000 samples of ADC counts in each cycle of 200 ms, I am still getting significant variations of ~ 5 uVp-p in ADC counts. I am able to reduce this variation further after averaging more number of samples but it slows the response.
Although, there are several other factors too for noise in the circuit as, INA output noise, thermal noise & current noise produced due to source resistance, ADC output noise etc.
I have connected REF2025's Vref to ADC ADS1271 and Vbias to AD8220 directly. I have also used 100nF and 2.2uF X7R bypass caps on Vref and Vbias.
I was wondering if someone can help me out in designing the REF2025 buffer filter to significantly reduce (<1uVp-p) 0.1Hz to 10Hz noise. I have OPA2140 in my mind, if it can be used in buffer for Vref and Vbias both of REF2025.
Thanks & Regards,
Harish KS