Download - noise.pptx
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Noise Coupling
Suresh Maddineni
7th June 2015
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The DIE:
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The Unwanted Loop:
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What is Inductance?:
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What is Loop Inductance?:
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Reducing Loop Inductance:
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Reducing Loop Inductance:
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Reducing Loop Inductance:
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Reducing Loop Inductance:
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Reducing Loop Inductance:
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What is left:
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Various currents
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De-caps
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De-caps are not ideal
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Several De-caps of different values
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RF channel:
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What makes sense:
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Anatomy of a smartphone:
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What is dBm?
Consider an amplifier with equal i/p and o/p impedances , Ro:
= = Av (dB)
In RF systems, the i/p and o/p impedances are unequal. Hence the absolute signal levels are expressed in dBm.
Examples: 0dBm = 1mW , i.e, a sinusoid with Vpp = 632mV in 50ohm resistor.Thus, -100 dBm is 6.32 uV peak-peak.
A GSM TX must deliver atleast 2W ( +33dBm) in the 900Mhz band. Depending on the distance from the base station, this power must be adjustable insteps of +5dBm.
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TREX:
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ESD GSM Filter Structure: AFE2410
Same as T1329B0 Different trex_hv layout from T1329B0- designed to improve
performance at lower alphas
hv_swt pad42Ω
6pF
6pF
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Test Bench: Abs multi-block tb
Input an 800MHz RF signal after some simulation time and measure the shift in the charge integrator output
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TREX:
The GSM noise source is represented by variable amplitude Psin source of 800MHz with 50 ohms source impendence, 75 ohms termination, and 10pf coupling capacitor to the receiver TREX
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Theory: Useful Formulae
----------------------------------,1----------------------------, 2
From 1, ------------------- , then
Also, ----------------------------------------------, 3
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Theory: Diagram
After GSMfilter
pad
42Ω6pF
6pF 75Ω
800MHz RF source3nH 10pF
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Theory: Voltage at the Pad
For the case @ power of 20dBm, with an RF signal (sine wave) of 800MHz: C = 10pF, L = 3nH, R = 75 Ohms
| = 34, then,
Thus, the
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Theory: Voltage after GSM filter
After resistor and capacitor network, = 54(1 – (54/75) = 1.134VThus, the voltage after the GSM filter should be approximately 1.134V
After GSMfilter
pad
42Ω6pF
6pF
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t1326 Transcap Mode Multi-block Test bench(w/Local CBC)
w/o GSM Noise
Rterm = 75ohms, Rsrc = 50ohms, Prf=20dbmFrf=800Mhz, Ccc=10pf
zero_cbc_gain 1ct_rcvr_multiplier 17(=4.25pf)cbc_global_out_sw 1static_cbc_global_res_adj 0static_cbc_global_bias_boost 0static_cbc_global_cap_sel 4td 10nRfb 0R 0Cfb0 0Cfb1 1.15*19.092pinp_swt_res 100Ccbc 1*8pabs_en 1cbc_abs_timing_mode 1cbc_hv_en 1cbc_pad_en 0R_routing 218C_routing 0CbRx 1.5palpha 0cfb1_val 0cfb_val 7cbc_cap 5(=3.0pf)cp_en 1supply 3ibais 1ut_clk 33.33nrstrch_cyc 0rst_cyc 6strch_cyc 0integ_cyc 60NTx 18NRx 32Ct 1pCbTx 1.5pCb1 5pCb2 2pRRx 50/2RTx 20/2ds_cyc 5RESET_DUR 10reset_cyc 10vin_lo_pull_up 1.65vin_hi_pull_dn 1.65
Test
be
nch
V
aria
ble
Set
tin
gs
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Ci_out w/o GSM Noise Ci_out with GSM noise
Ci_out_neg = 1.2405V
Ci_out_pos = 1.737V
Ci_out_pos = 1.7403V
Ci_out_neg = 1.247V
w/o GSM with 20dbm GSM Delta(mV)Ci_out pos 1.7403 V 1.737 2.8Ci_out neg 1.2405 V 1.247 -6.5
t1326 Transcap Mode GSM Sims(20dbm, Ct=4.25pf, Cbc=3pf)
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t1326 Transcap Mode GSM Sims(20dbm, Ct=1pf, Cbc=1pf)
Ci_out w/o GSM Noise Ci_out with GSM noise
Ci_out_pos = 1.490V
Ci_out_pos = 1.486V
Ci_out_neg = 1.489V
Ci_out_neg = 1.487V
w/o GSM with 20dbm GSM Delta(mV)Ci_out pos 1.490 V 1.486 4.0Ci_out neg 1.489 V 1.487 3.0
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Thank You !!