RF Front End Radio Design- Simulations and Specifications

RF Front End Radio Design-Simulations and Specifications

Hemish ParikhAdvisor: Prof. William R. Michalson

04/22/23 2

Outline• Overview• System parameters• Specifications• System Analysis• System Parameter relations• System Simulations in ADS• Roadmap• Questions

RF Front End Receiver Design - Outline

04/22/23 3

Filters, Amps

Mixers, Osc

Analog Front End Location Estimate

A/D, Latches,

SDRAM

Digital Back End

Vin

GND

Vref

D1

D4

Sign

ENB

Vref

FB

Comp

Reset

I-sense

Drain

Source

Shtdwn

Interface

Overview

RF Front End Receiver Design - Overview

You are Here

04/22/23 4

Today’s Focus

A/DAMP

LO

BPF MIXER DSPLPF

Possible Front End ModelsPossible Front End Models• Model 1: Direct RF Sampling

• Model 2: Direct Down Conversion

A/DAMPBPF DSP

880 MHz

RF Front End Receiver Design - Overview

04/22/23 5

System Parameters

• System Gain (G)• System Noise Figure (NF)• Input 3rd Order Intercept Point (IIP3)• Receiver Sensitivity (Rx-Sens)• Receiver Spurious Free Dynamic Range

(SFDR)• Inter Modulation Distortion (IMD)

RF Front End Receiver Design – System Parameters

04/22/23 6

Component Identification

AGC

VCO

BPF MIXER LPF

PLL

TCXO

LNA

0-50 MHz

COMTELCO

PEXW-400

MURATA

415-465 MHz

ANALOG DEVICES

AD-8343

MURATA

0-50 MHzVARI-L

VCO190-445T

VECTRON

OSC-1B0-10MHzANALOG DEVICES

ADF-4112

ANALOG DEVICES

AD-8367

RF MICRO DEVICES

RF-2361

RF Front End Receiver Design - Specifications

04/22/23 7

Specifications - LNA

• RFMD – 2361– Low Noise Figure (NF): 1.9 dB– Gain (G): 20 dB– Input 3rd order intercept point (IIP3): 6 dBm– Max input RF level: +10 dBm

AGCBPF MIXER LPFLNAP_in P_out


04/22/23 8

Specifications - AGC

• AD 8367:– Variable Gain:

-2.5 dB to 42.5 dB– NF ???– IIP3 ???



mVmVVVdBGain

Gain

Gain

95050550)(

04/22/23 9

Specifications – Mixer (1)

• Big role in overall system performance• Mixing is just frequency shifting• Produces LO+RF and LO-RF• Produces Unwanted Inter Modulation Distortion (IMD)• IM products: (M*LO + N*RF) and (M*LO - N*RF)• Good Mixer or a Bad Mixer !!!!!????

RFLO

LO-RF LO+RF

IM Products


04/22/23 10

Good Mixer

Low Noise Figure (< 15dB)

Good Port Isolation (~ 50dBm)

High IP3 ( > 15dB)

High Conversion Gain

LO drive level (application dependent)



04/22/23 11

• AD 8343:– NF: 11 dB– Gain: 7.1 dB– IIP3: 20 dBm– LO drive level: -10 dBm




04/22/23 12

MIXER

m14freq=dBm(V_input)=-9.172

40.00MHz

0.5 1.0 1.5 2.0 2.5 3.00.0 3.5

-200

-100

-300

0

freq, GHz

dBm

(V_i

nput

)

Readout

m14 Mixer Input

m1freq=dBm(Vmix)=-15.926

440.0MHzm7freq=dBm(Vmix)=-12.433

360.0MHz

0.6 1.1 1.6 2.1 2.6 3.10.1 3.5

-100

-50

-150

0

freq, GHz

dBm

(Vm

ix)

Readout

m1

Readout

m7Mixer Output



LO = 400 MHz

04/22/23 13

Specifications - TCXO / VCO

• Vectron TCXO:

– Frequency: 10 MHz– Stability: 2.5 ppm– Mechanical Trip:

+/- 3 ppm

• Vari-L VCO:

– Tuning Range: 400 to 500 MHz

– Tuning Sensitivity: 15MHz/V

AGC

VCO

MIXER

PLL

TCXO

LNA


04/22/23 14

Specifications – PLL (1)

• ADF 4113:– Programmable

counters: P, B, A, R

AGC

VCO

MIXER

PLL

TCXO

LNA

RfABPf TCXOvco /


04/22/23 15

System Gain

G1= -2dB G2= 20dB G3= 7.1dB G4= -2dB

BPF LNA MIXER LPF

P_in (dBm) -40 -42 -22 -14.9

Gain (dB) -2 20 7.1 -2

Cumulative Gain -2 18 25.1 23.1

P_out (dBm) -42 -22 -14.9 -12.9

G(dB) = G1+G2+G3+G4

P_in = G + P_out

BPF MIXER LPFLNAP_in P_out

RF Front End Receiver Design – Analysis

04/22/23 16

System Noise Figure (1)Noise Sources

System Noise Thermal Noise

System noisy due to losses in circuit, solid state devices.

Noise Figure quantifies

how noisy the system is

Noise Figure is Noise Factor in dB

GOAL: Design receiver with lowest NF !!!!!!

Reference Max allowed NF: WCDMA: 9 dB

Cellular: 10 dB PCS: 6.8 dB


04/22/23 17

System Noise Figure (2)

BPF LNA MIXER LPF

NF (dB) 2 1.9 11 2

Cumulative NF (dB)

2 3.9 4.21 4.22

.....1

1

21

GNFNFNFNoise Figure of Cascaded System

NF1=2dB NF2=1.9dB NF4=11dB NF5= 2dB

G1= -2dB G2= 20dB G3= 7.1dB G4= -2dB


Critical


04/22/23 18

System Input IP3 (1)

IP3 is a measure of system linearity. Point where the desired signal and the 3rd order

distortion have equal magnitudes.

Third Order products: 2f1+f2, 2f1-f2, 2f2+f1, 2f2-f1, where f1 and f2 are two

inputs.

Problem: Relatively large magnitude and difficult to filter

Reference Min allowed IIP3:Cellular: -13 dBmPCS: -11.425 dBm


04/22/23 19

System Input IP3 (2)

G1= -2dB G2=20dB G3=7.1dB G4= -2dB

IIP1= dBm IIP2= 6dBm IIP3=20dBm IIP4= dBm

1

43213

1111log10

IPIPIPIPIIP

dBm1.1)28.1log(10

16.1

131.611log10

1


Critical


04/22/23 20

Rx. Sens = Noise Floor + 10log(BW) + SNR_min + Noise Figure

Significantly reducesThe Rx. Sens

Receiver Sensitivity (1)• Rx. Sens quantifies the receivers ability to respond

to weak signal.

Rx. Sens = -174 + 77 + 12 + 4.22 = -80.78 dBm

SNR_min = 12dB (Assume)BW = 50MHz



A/DInput

04/22/23 21

Receiver Sensitivity (2)


As BW increases, sensitivity becomes poor

04/22/23 22

Receiver Sensitivity (3)


04/22/23 23

Receiver Spurious FreeDynamic Range

• High DR means Receiver can operate over wide range of input power levels.– Receiver’s Output starts to saturate if the Input is above

the range– Below DR, the noise dominates.

SFDR = 0.66 (IIP3 – Rx. Sens)

= 0.66 (1.1 + 80.78)

= 54.6 dB


04/22/23 24

AGC Issues

• Max AGC Gain: – Lowest NF– Lowest IIP3


• Min AGC Gain: – High IIP3– High NF

• Poor Dynamic Range: 25dB

04/22/23 25

DynamicRange

dBm

NoiseFigure

Min SNRReqd

Approx:IP3-15

Min Reqd Rx.Signal Level

Effective Rx. Noise= -90dBm

Thermal NoiseFloor

System Parameters Relations

Application Dependent

Maximize Rx. Sens

Maximize DR

Higher IP3

Bandwidth Dependent

Minimize NF

RF Front End Receiver Design – Parameters Relations

04/22/23 26

ADS simulations for Gain (1)

m2Component=our_bgain[0::x,0]=22.375

b6

b2_AMP1 b3_MIX1 b5_BPF2b1_BPF1 b6

0

10

20

-10

30

Component

our_

bgai

n[0:

:x,0

]

Readout

m2Gain in the Receive RF chain


RF Front End Receiver Design - Simulations

04/22/23 27

ADS simulations for Gain (2)

m1Component=our_bgain[0::x,0]=22.018

b6

b2_BPF1 b3_MIX1 b5_BPF2b1_AMP1 b6

0

10

20

-10

30

Component

our_

bgai

n[0:

:x,0

]

Readout

m1Gain in the Receive RF chain

MIXERBPF LPFLNAP_in P_out

Swapped


04/22/23 28

ADS simulations for NF(1)

m1Component=our_bnf[0::x,0]=4.259

b6

b2_AMP1 b3_MIX1 b5_BPF2b1_BPF1 b6

1

234

0

5

Component

our_

bnf[0

::x,0

]

b64.259

m1NF in the Receive RF chain



04/22/23 29

ADS simulations for NF(2)MIXERBPF LPFLNA

P_in P_out

Swapped m5Component=our_bnf[0::x,0]=2.468

b6

b2_BPF1 b3_MIX1 b5_BPF2b1_AMP1 b6

0.5

1.0

1.5

2.0

0.0

2.5

Component

our_

bnf[0

::x,0

]

Readout

m5NF in the Receive RF chain


04/22/23 30

BPF2_in

Mix2_in LPF1_in

Mix1_in BPF1_in

LPF1_out

Amp1_in

Amp2_in

Link1_in

MixerIMTMIX2

IMT_File="dbl1.imt"LoThresh=NF=11 dBS33=0.S22=0.3S11=0.3ConvGain=dbpolar(7.1,0)

MixerIMTMIX1

IMT_File="dbl1.imt"LoThresh=NF=17 dBS33=0.S22=0.3S11=0.3ConvGain=dbpolar(7.1,0)

BPF_ChebyshevBPF1

IL=2 dBBWstop=100 MHzBWpass=80 MHzFcenter=440 MHz

LPF_ButterworthLPF1

IL=2 dBAstop=20 dBFstop=75 MHzApass=3 dBFpass=50 MHz

AmplifierAMP1

S12=0.S22=0.3S11=0.3S21=dbpolar(33,0)

LOS_LinkLINK1

PathLength=10 meterRxVSWR=1.5RxGain=1 dBTxVSWR=1.5TxGain=1 dBBW=112 MHzCenterFreq=440 MHzP_1Tone

SRC2

Freq=465 MHzP=dbmtow(0)Z=50 OhmNum=3

TermTerm1

Z=50 OhmNum=2

BPF_ChebyshevBPF2

IL=2 dBBWstop=75 MHzBWpass=50 MHzFcenter=440 MHz

P_nTonePORT5

P[5]=dbmtow(-10)P[4]=dbmtow(-10)P[3]=dbmtow(-10)P[2]=dbmtow(-10)P[1]=dbmtow(-10)Freq[5]=45 MHzFreq[4]=35 MHzFreq[3]=25 MHzFreq[2]=15 MHzFreq[1]=5 MHzZ=50 OhmNum=5

AmplifierAMP2

S12=0.S22=0.3S11=0.3S21=dbpolar(20,0)

P_1ToneSRC3

Freq=465 MHzP=dbmtow(7)Z=50 OhmNum=4

ADS simulations for IMD (1)


04/22/23 31


0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-100-80-60-40-20

-120

0

freq, GHz

dBm

(Mix

1_in

)

Original Signal

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-100-80-60-40-20

-120

0

freq, GHz

dB(B

PF1_

in)

UpConvertion Mixer Output

300 500 700100 900

-300

-200

-100

0

-400

50

freq, MHz

dBm

(Lin

k1_i

n)

Transmitted Signal


300 500 700100 900

-400

-300

-200

-100

-500

0

freq, MHz

dBm

(Am

p2_i

n)

Receiver LNA input

04/22/23 32


200 400 6000 800

-100-80-60-40-20

0

-120

20

freq, MHz

dBm

(Mix

2_in

)

Downconverter Mixer Input

200 400 6000 800

-100-80-60-40-20

0

-120

20

freq, MHz

dBm

(LPF

1_in

)

Downconverter Mixer Output

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-250-200-150-100-50

-300

0

freq, GHz

dBm

(LPF

1_ou

t)

LPF output

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-250-200-150-100-50

-300

0

freq, GHz

dBm

(Mix

1_in

)

Original Signal


04/22/23 33

ADS simulations for SFDR

0.2 0.4 0.6 0.8 1.0 1.20.0 1.4

-100-80-60-40-20

-120

0

freq, GHz

dBm

(LPF

1_ou

t)

LPF output


Rx Signal Level = -25dBm

SFDR ~= 50 dB

SFDR

04/22/23 34


04/22/23 35

Roadmap

• ADS with Matlab• ADS with Instruments• Set-up Evaluation board• Migrate to 2.4 GHz

RF Front End Receiver Design

04/22/23 36

RF Front End Receiver Design

?

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RF Front End Radio Design- Simulations and Specifications

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