Link Budget and System Architecture Advanced System Design Informational

How do I design a frequency plan for a multi-band multi-standard radio covering LTE and 5G NR?

Designing a frequency plan for a multi-band, multi-standard radio covering LTE and 5G NR requires selecting the local oscillator (LO) frequencies and IF frequencies for each band to ensure that all bands can be received and transmitted without any spurious signals falling within the desired signal bandwidth. The design involves: listing all required bands (LTE bands: B1 (2100 MHz), B3 (1800 MHz), B7 (2600 MHz), B20 (800 MHz), etc.; 5G NR bands: n77 (3300-4200 MHz), n78 (3300-3800 MHz), n79 (4400-5000 MHz), n257/n258/n260/n261 (mmW bands); each band has defined uplink and downlink frequency ranges), selecting the receiver architecture (direct conversion (zero-IF): the LO frequency equals the center frequency of the desired band; simplest architecture but requires DC offset and I/Q imbalance calibration. Low-IF: LO offset by a small IF (1-10 MHz) to avoid DC issues. Superheterodyne: one or two IF stages with fixed IF frequency; provides the best selectivity and spurious performance), computing all spurious frequencies for each LO setting (for each combination of RF and LO frequencies: calculate the mixing products at m x f_RF ± n x f_LO for m, n = 0, 1, 2, 3, ...; identify any spurious products that fall within any of the desired receive or transmit bands), optimizing the LO frequencies to minimize in-band spurious products (this is an iterative process, often aided by software tools that evaluate thousands of LO/IF combinations and rank them by the severity of spurious products; the goal is to find LO/IF combinations where no significant spurious product falls within any receive band), and verifying the frequency plan with system simulation (simulate the complete receiver chain with realistic mixer nonlinearity to confirm that all spurious products are below the required level, typically -70 to -90 dBc).

Category: Link Budget and System Architecture

Updated: April 2026

Product Tie-In: System Components

Multi-Band Radio Frequency Planning

Frequency planning is one of the most critical system design tasks for a multi-band radio because a poor frequency plan can create spurious responses that cannot be filtered out, permanently limiting the radio's performance.

Parameter	Free Space	Urban	Indoor
Path Loss Model	Friis (1/r²)	Okumura-Hata	IEEE 802.11
Fading Margin	0 dB	10-30 dB	5-15 dB
Multipath	None	Severe	Moderate-severe
Typical Range	Line of sight	1-30 km	10-100 m
Shadow Fading (σ)	0 dB	6-12 dB	3-8 dB

Margin Allocation

When evaluating design a frequency plan for a multi-band multi-standard radio covering lte and 5g nr?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Performance verification: confirm specifications against the application requirements before finalizing the design
Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades

Propagation Modeling

When evaluating design a frequency plan for a multi-band multi-standard radio covering lte and 5g nr?, engineers must account for the specific requirements of their target application. The optimal choice depends on the frequency range, power level, environmental conditions, and cost constraints of the overall system design.

Common Questions

Frequently Asked Questions

How do I handle simultaneous multi-band operation?

Carrier aggregation in LTE and 5G NR requires receiving multiple bands simultaneously. Each band needs its own LO and receive chain. The frequency plan must ensure: no LO from one band creates a spurious product that falls in another band's receive window, the LO harmonics do not interfere (LO harmonics at 2×f_LO, 3×f_LO can fall in adjacent bands), and the transmitter of one band does not desensitize the receiver of another band (TX-RX isolation and filtering are critical). This analysis becomes exponentially complex with more bands.

What tools help with frequency planning?

Keysight SystemVue: system-level simulation tool that can evaluate mixing spur charts for complex multi-stage receivers. National Instruments AWR VSS: system simulation with spur analysis capability. Custom spreadsheet or Python tools: many engineers develop their own spur analysis tools that iterate through all m,n combinations and check for in-band spurious products. Spurs are typically analyzed to order 5×5 (m,n up to 5), which covers the most significant products.

What about 5G mmW bands?

For 5G mmW (24-40 GHz): the frequency plan uses a two-stage superheterodyne (RF to IF at approximately 5-10 GHz, then IF to baseband) or direct conversion with a very high frequency LO. The mmW LO is typically generated by a lower frequency synthesizer with a frequency multiplier (e.g., 10 GHz VCO × 3 = 30 GHz LO). Spur analysis must include the multiplier harmonics: if the LO multiplier generates harmonics at 2×, 3×, 4× the input frequency, all of these can create spurious products. The frequency plan must ensure none of these fall in-band.

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